FA-127, January 1993

Basic Toolsand Resourcesfor FireInvestigators:A Handbook

Federal Emergency Management Agency

United States Fire Administration

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BASIC TOOLS AND RESOURCESFOR

FIRE INVESTIGATORS:A HANDBOOK

FEDERAL EMERGENCY MANAGEMENT AGENCYUNITED STATES FIRE ADMINISTRATION

September 1992

TABLE OF CONTENTS

Chapter 1 - OVERVIEWPURPOSE OF THIS HANDBOOKRESEARCH METHOD

Published Request ResponsesInterviews

SUMMARY OF FINDINGSBasic Tools and EquipmentAccelerant DetectionCollection, Packaging, and Analysis of EvidenceComputersInformation Resources

ORGANIZATION OF THIS REPORT

Chapter 2 - FIELD INVESTIGATION TOOLSHAND TOOLS AND BASIC EQUIPMENTEVIDENCE COLLECTION EQUIPMENT

Essential EquipmentDesirable Equipment

PERSONAL AND PROTECTIVE EQUIPMENTPersonal Protective EquipmentLaw Enforcement Equipment

COMMUNICATIONS EQUIPMENTFIRE INVESTIGATION VEHICLES

Chapter 3 - ACCELERANT DETECTIONOVERVIEWMECHANICAL AND ELECTRONIC EQUIPMENT

Catalytic Combustion DetectorsPhoto-ionization DetectorsSemiconductor or Toguchi Sensor InstrumentsFlame Ionization Detectors

ACCELERANT DETECTION CANINESTraining ProgramsSupport

Chapter 4 - COLLECTION, PACKAGING, AND ANALYSIS OF EVIDENCEFIRE SCENE SAMPLING

Accelerant Residue SamplesTrace EvidenceComparison Samples

EVIDENCE PACKAGINGAccelerant Residue SamplesTrace EvidenceComparison SamplesStorage and Preservation of Evidence

FORENSIC TECHNIQUESAccelerant IdentificationSample PreparationInstrumental AnalysisData AnalysisExamination of Trace EvidenceComparison of Evidence Samples

111112222333

4444445555

6666888889

10IO101112131313141414141515171718

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PHOTOGRAPHIC PROCESSING AND ANALYSIS 18Fire Scene Photography 18Photographic Equipment and Techniques 20Using Fire Scene Photographs 21

Chapter 5 - COMPUTER SYSTEMS 23HARDWARE 23APPLICATION PROGRAMS 23

Word Processing 24Database Management 24Spreadsheets . 24Graphics 25Computer Communications 25

FIRE MODELING SOFTWARE 26

Chapter 6 - INFORMATION RESOURCES 27THE FIRE INVESTIGATOR’S REFERENCE LIST. 27JOURNALS AND PERIODICALS 27PROCEEDINGS 29ELECTRONIC INFORMATION SERVICES 29

Specialized Electronic Reference Sources 29Fire Service Bulletin Boards 29

UNITED STATES FIRE ADMINISTRATION PUBLICATIONS 29

BIBLIOGRAPHY 31APPENDIX A 34APPENDIX B 37

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Chapter 1OVERVIEW

PURPOSE OF THIS HANDBOOK

This handbook is designed to serve as a compendium ofbasic information about the tools and techniques of fireinvestigation. The goal here is to provide a breadth of usefulinformation in as concise and as accessible a package aspossible. To do this, the scope has been limited to the toolsand techniques associated with determining and verifyingthe origin and cause of accidental and incendiary fires. Thisis not a law enforcement procedures manual, informationabout surveillance, criminal identification, interview andinterrogation procedures, insurance fraud, and proceduresrelated to investigating other criminal activities often asso-ciated with arson are not described here. Information aboutpresentation of fire-related evidence in criminal and civiltrials is only discussed in the context of how it relates to theadvantages and disadvantages of specific techniques.

RESEARCH METHOD

The information in this handbook has been assembled froma wide array of sources, including the fire investigation andforensic science literature, interviews with experts in fireinvestigation and forensic science practitioners, and thenationally recognized standards of practice for fire investi-gation and forensic science. Members of both professionsfrom across the country, and in one case another country -Australia - have lent their considerable experience andexpertise to this project by responding to published requestsfor information and participating in interviews about whatthey do and how they do it.

Published Request Responses

The published requests for information were circulated to allof the major fire service, fire investigation, code enforce-ment, and fire protection publications asking investigatorsto respond to the following questions:

What basic tools are issued to all yourinvestigators? (Please provide lists)

What equipment not currently avail-able to you do you most need?? (Pleaseidentify)

Do you currently use canines in fireinvestigation? Are they certified? Havetheir findings held up in court?

What type of gas chromatograph do youuse? How has it performed?

Where do you send your evidence - toyour own lab, the police departmentlab, a state lab or a private lab?

Useful responses were received from 29 fire investigationunits. These agencies, shown on page 2, represented alltypes of fire investigation units, career and volunteer, froma diverse range of communities large and small, urban,suburban, and rural. Agencies from different levels ofgovernment responded as well, including state fire marshal’soffices, county fire investigation units, and local fire inves-tigators. Two encouraging results were apparent from thenature and diversity of the responses. First, that despite theirdifferences, all of these jurisdictions had many things incommon about the way they conducted fire investigationsand what they used to do this. The other was just as important- that despite the similarities, there was no single way to doeverything.

These responses provided valuable insight into the admin-istrative environment in the fire investigation field.

I n t e r v i e w s

To corroborate and further expand on the findings of thepublication responses, a series of interviews with local,state, and federal fire investigators and laboratory personnelfrom across the nation was conducted. The agencies in-volved are shown on page 2. These interviews providedadditional insight and valuable background informationabout the use of technology, disputes about techniques, andthe advantages and disadvantages of various methods orprocedures.

As a result of these responses, this handbook tries to do threethings:

Explain what is out there and how it is used;

Explain how much things cost and whatadvantages, disadvantages, costs, and ben-efits are associated with the tools and tech-niques described;

And, explain what constitutes a goodbasic or minimum complement of tools,equipment, and technical capability.

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Fire Investigation UnitsResponding to Request for Information

Allentown Fire Department, PAAtlantic County Prosecutor’s Office, NJ

California State Fire Marshal’s Office, CAChino Valley Fire Department; CA

Cincinnati Division of Fire, OHClark County Fire Department, NV

Colerain Township Fire Department, OH’District Six Volunteer Fire Dept., Baton Rouge, LA

Gainesville Fire/Rescue Department, FLHall County Public Safety Department, GA

Hartford Fire Department, CTKent Fire Department, WA

Lewis County Fire Investigation Unit, NYMaryland State Fire Marshal’s Office, MD

Metropolitan Fire Brigades Board, Melbourne, AustraliaMokena Fire Protection District, IL

Moss Township Fire Department, MSOrange County Fire Department, CA

Palm Bay Fire Department, CAPiqua Fire Department, OH

Riley Township-Pandora Volunteer Fire Dept., OHRogers Fire Department, AR

San Mateo Arson Task Force, CASellersburg Fire Department, IN

South Kitsap Fire Department, WAVentura County Fire Protection District, CA

Vineland Fire Department, CTWindsor Fire Department, CT

Wyoming Dept. of Fire Prevention and Electrical Safety, WY

Agencies Interviewed

Arkansas Department of State Police, Fire Marshal SectionU. S. Department of the Treasury, Bureau of

Alcohol, Tobacco, and FirearmsConnecticut State Police, Canine Section

Eastern Kentucky University, Department of LossPrevention and Safety

Florida Division of State Fire MarshalInsurance Committee for Arson Control

lnternational Association of Arson Investigation, ForensicScience and Training and Education Committees

Minnesota State Fire Marshal DivisionNebraska State Fire Marshal’s Office

Oklahoma City Fire Department, OKPennsylvania State Police, Fire Marshal Division

Portland Fire Bureau, ORWyoming Dept. of Fire Prevention and Electrical Safety

SUMMARY OF FINDINGS:

Basic Tools and Equipment

Fire investigators are using a wide variety ‘of tools andequipment in their work. Many of these are commonplace,others quite unique and sophisticated. Many departmentshave either acquired or desire electronic equipment likevideo cameras, cellular telephones, facsimile machines, andpersonal computers. A decided trend throughout the public-safety field which was not strongly demonstrated by thepublication responses but reinforced during interviews, wasthe need for personal protective equipment for fire investi-gators. Several fire investigation professionals pointed outthe riced for respiratory protective equipment, and one notedthe need for latex gloves for preventing contact with blood-borne pathogens. Yet another office discussed the need forHepatitis B vaccinations for its employees. Many agenciesemployed sworn law enforcement officers who were issuedfirearms, ammunition, handcuffs, and ballistic vests.

Accelerant Detect ion

A traditional law enforcement approach - the use ofcanines for detection purposes - is gaining popularity foraccelerant residue detection. Hand-held electronic “sniff-ers” remain popular as well. Some agencies use bothtechniques in tandem to increase their sampling confidence.Both techniques have their proponents. Both have becomewell-established means of identifying accelerant residuesamples for collection and analysis. Likewise, both havebeen accepted in court. So far, no one is reporting anyproblems with canine evidence in court proceedings. How-ever, many forensic science professionals caution that ifrigorous training and certification standards are not estab-lished and maintained, this excellent record may be injeopardy.

Collection; Packaging, and Analysis of Evidence

Much of the early attention here focused on laboratorytechniques, but as work progressed it became evident thatprocedures for collecting, packaging, and storing evidencewere equally if not more important. Analysts interviewedduring the development of this manual and published ar-ticles in the literature emphasized that evidence which is notcollected or which is collected or handled improperly willseverely compromise any investigation. Since no clearguidelines exist on what evidence or how many samples tocollect, interest shifted to determining if guidelines werediscernable from the current practices in the field. Advancesin packaging technologies have introduced a few innova-tions, such as KapakTM bags which are resistant to vaporleakage, but the best evidence containers for accelerantresidue samples remain clean metal paint cans with frictionlids. Beyond collection and packaging, the nature of the fire

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scenario and, the types of evidence submitted to the labora-tory determine how it is processed by the forensic sciencetechnicians. The effectiveness of, an analysis is heavilyinfluenced by communication between the field investigatorand the laboratory analyst.

Computers

The use of computers in the fire service has been growing aselsewhere in business and government. Federal efforts todevelop useful computer-aided tools for fire investigatorsbegan in the early 1980s with the United States FireAdministration’s development of the Arson InformationManagement System (AIMS). Literature research andinterviews revealed that a large number of commercialproducts exist which, follow the AIMS lead. Also, a widevariety of application programs exist for word processing,database management, graphics, communications, and nu-merical analysis. As these programs have become more“user-friendly” they have become more popular among fireinvestigators. Investigators can use most of the popularcommercial programs for writing reports, preparing firescene diagrams, maintaining investigation records, analyz-ing financial information and fire statistics, and communi-cating with other fire protection and law enforcement pro-fessionals via electronic information services. The horizonfor use of computers in the fire service continues expandingwith the introduction of increasingly sophisticated computerfire models for analyzing complex fire protection problems.Programs like the National institute for Standards andTechnology, Building and Fire Research Laboratory’s (NlST/BFRL) HAZARD I model are designed to be easier learnand use. These programs offer fire investigators a set of toolsfor understanding and documenting what happened in firesthey investigate.

Information Resources

All complex, fields of knowledge are under continuousrevision and interpretation. Fire investigation and firescience are certainly no exceptions. Keeping well-informedand current is a constant challenge. Fortunately, fire inves-tigators have access to a wide array of information resources,including periodicals, books and texts, codes and standards,on-line information services, and conference proceedings.The federal government maintains: a large number of refer-ence sources for fire investigators, including the Fire andArson Investigators’ Field Index Directory, Arson ResourceDirectory, Establishing an Arson Strike Force, and A Viewof Management in Fire Investigation Units.

ORGANIZATION OF THIS REPORT

The authors chose to organize this handbook much the sameway a good investigator conducts an origin and causeinquiry. The fire investigator works from the least burnedor damaged area to the most heavily damaged area in asystematic fashion, collects information and evidence, pro-cesses the information, analyzes the results and presents hisor her case to a prosecutor and/or court. This handbookworks from the hardware, tools, and equipment used at thefire scene to the scientific and technical information andanalysis necessary to resolve a complex case.

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Chapter 2FIELD INVESTIGATION TOOLS

The most important fire investigation field tools are keenobservational skills, innate curiosity, and an interest indetermining the truth. This section details the hardwarerequired to put the basic tools of intellect, observation, andperseverance to work in a difficult and challenging environ-ment - the fire scene. The utility of all of these tools andequipment can be expanded by proper training and use.

This discussion includes accidental and incendiary alike.Some of the tools discussed are considered useful in deter-mining the origin or cause of either incendiary or accidentalfires, most are useful in investigating both types of fires.

HAND TOOLS AND BASIC EQUIPMENT

Fire investigators must perform many of the tasks associatedwith overhaul in the process of identifying and eliminatingpotential ignition sources, collecting evidence, and deter-mining the mechanisms of fire behavior and fire spread.Some simple hand tools and other equipment should becarried by or be available to fire investigators to performtasks such as disassembling equipment, opening packages,removing interior finish and trim, and obtaining evidencesamples. The following sections detail the equipmentinvestigators say they use to perform many routine fireinvestigation tasks. These items include tools for cutting,drilling, prying, loosening, and measuring. A complete listof these tools appears in Appendix A.

EVIDENCE COLLECTION EQUIPMENT

Evidence collection and preservation is one of the mostimportant tasks associated with fire investigation. Every-thing needed to confirm the cause, origin, or contributingfactors associated with a particular fire must be collected andcatalogued. In the case of incendiary and suspicious fires,evidence about suspects and people associated with thepremises or the fire scene must be collected and preservedas well.

Essential Equipment

Key tools associated with these tasks include equipment forphotographing, collecting, marking, and preserving firescene debris samples, materials for documenting and dia-gramming the overall condition of the scene, and tools forcollecting the statements and accounts of witnesses. A listof basic evidence collection equipment appears in AppendixA. Many of the items on that list are quite costly. Somedepartments with limited budgets will find it necessary tolimit their equipment to the bare essentials. Some of the

basic evidence collection equipment may include a simple35-mm automatic camera, a small assortment of evidence

containers, a measuring tape or rule, and drawing andwriting supplies.

Desirable Equipment

Many agencies have acquired video camcorders, videocas-sette recorders, and videotape editing machines or placedthem high on their “wish lists.” Video and advancedtelecommunications are two of the fastest growing capabili-ties of most fire investigation units. Although sophisticatedhigh-resolution video camcorders capable of operating inlow-light-level conditions costs approximately $2,000, areasonable videotape camcorder and playback unit can beobtained for less than $1,200. Videotape capability hasbecome so popular so quickly because it provides theinvestigator with a tool for capturing action and document-ing the fire scene while maintaining spatial and temporalperspective. Moreover, when the fire investigator can arriveat the scene before the fire is extinguished, videotape is afarsuperior method of capturing live action fire sequences forreconstructing the fire scenario later.

The use of videotape as a law enforcement and investigationtool has become so commonplace that many law enforce-ment agencies have begun mounting videotape cameras intheir vehicles to record routine traffic stops. Following suit,some fire departments are considering installing videocamcorders in fire apparatus to record fire operations.Likewise, many fire investigation units use video camcord-ers to routinely record the crowds assembled at fire scenesto identify possible arson suspects. All of these applicationsare significantly enhanced by editing capability. Rawvideotape can be edited and captioned to reinforce keypoints for training purposes or to highlight key points whenused for presentation at trial.

PERSONAL AND PROTECTIVEEQUIPMENT

Most fire investigators assigned to fire service or lawenforcement units will need some basic equipment for theirpersonal use and protection. Items like badges, ID cards,business cards, and uniforms help identify them to thepublic, which can cut two ways: it can help protect them oridentify them as a target. Items like flashlights and clip-boards are basic tools for most investigators as well. Firescenes are inherently dangerous places to work; therefore,protective equipment should be provided to minimize therisk of personal injury. A list of personal and protectiveequipment appears in Appendix A.

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Personal Protective Equipment

In recent years, increased awareness of the hazards tofirefighters have produced significant improvements inpersonal protective equipment. However, the hazards to fireinvestigators are often given inadequate consideration. Justbecause the fire is out does not mean the hazard has passed.Toxic combustion products like carbon monoxide, carbondioxide, cyanides, sulphur dioxide, hydrogen sulfide, acro-lein, nitrogen oxides, and other substances exposed by thefire such as asbestos are just a few of the toxic inhalationhazards present on the fireground after a fire is extinguished.Fire weakened and water-logged structures present thecontinuing danger of collapse; and, sharp objects and de-formed materials may present trip, fall, or abrasion hazards.In short, the fireground only becomes marginally less haz-ardous after the fire is out, and fire investigators mustrecognize and protect themselves from many of the samehazards as firefighters. These include the hazards of acuteexposures which may incapacitate an investigator immedi-ately and those which produce chronic or long-term healtheffects which produce gradual debilitation.

Many investigation units now issue their investigators half-mask respirators and air monitoring equipment to guardagainst fireground inhalation hazards. The most popularfilters for use with these respirators are designed to filter outvolatile organic chemicals, acid vapors, and particulate. Airmonitoring equipment is used to detect and alarm upon thepresence of diminished oxygen concentration or the pres-ence or elevated carbon monoxide levels.

Coveralls, steel toe, steel shank shoes or boots, hardhats orhelmets, firefighter turnout clothing, gloves, and gogglescomplete the fire investigator’s protective ensemble. Theseitems prevent injuries from abrasion, impact, and puncture.A list of protective equipment appears in Appendix A.

Law Enforcement Equipment

Some fire investigators have dual authority to investigatefires and make criminal arrests. Different duties come withthe added authority of sworn law enforcement officers.These factors also influence how the fire investigators, thepublic, and potential suspects may interact. Most lawenforcement officers not only possess the right to bearfirearms, but a duty to carry these weapons on and off-dutyas well. The risks associated with carrying and usingfirearms bear special consideration for fire investigators.The issuance and use of ballistic vests should be seriouslyconsidered anytime fire investigators will USC or carryfirearms, as well as when they expect them to be used againstthem. To further minimize the risks of bodily injury to themor members of the public, most law enforcement agenciesrequire suspects to be restrained when taken into custody. Assuch, handcuffs or other restraint devices should be issued

when the fire investigator’s authority and duties includearrest powers.

COMMUNICATIONS EQUIPMENT

The acquisition of communications equipment has becomeone of the top priorities of many fire investigation agencies.The reasons is clear: access to the right communicationsequipment saves a fire investigator time and enhances his orher ability to do a good job. With the costs dropping rapidly,most of these tools are now within easy reach of most publicagencies. However, while the costs of acquiring tools likecellular telephones or facsimile machines may be relativelylow, the cost of using and maintaining such services isusually higher than standard telephone service. Agenciesshould become familiar with the costs of operating cellulartelephones, pagers, and facsimile machines to prevent un-welcome surprises.

FIRE INVESTIGATION VEHICLES

Many agencies have found it desirable to have a dedicatedvehicle for transporting the wide array of tools and equip-ment they require to fire Scenes. Often these vehicles alsoserve as command posts. Like other fire service or lawenforcement vehicles, these “arson vans” are often highlyspecialized. Usually, a fire investigation field unit consistsof a van or truck with an enclosed cargo body. Most areequipped with emergency response equipment, public ad-dress systems; and radios. Field units of this type permit fireinvestigators to bring a wider variety of tools and equipmentto the scene than would be possible with a staff car. Someof these items include digging tools, salvage tools, and scenesecurity supplies. Some units are equipped with cellulartelephones, cellular facsimile machines, portable comput-ers, remote surveillance equipment, and forensic analysisequipment. The configuration of a local fire investigationfield unit should be tailored to the jurisdiction’s particularneeds and budget. State motor vehicle laws dictate the typesof warning equipment required if the unit will be used torespond to emergencies.

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Chapter 3ACCELERANT DETECTION

One of the principal techniques for evaluating whether a fireis incendiary is to test for the presence of flammable orcombustible liquid accelerants. This section presents themost widely used techniques for detecting the presence (notthe concentration) of flammable or combustible liquid ac-celerants in fire debris. Regardless of the investigativetechnique employed - analytic equipment, accelerant de-tection canines, or the investigator’s senses of sight, touch,and smell - its reliability is dependent upon experience andjudgement.

OVERVIEW

Eight types of field tests or instruments are recognized asvalid for detecting the presence of flammable liquid vaporsat fire scenes. However, only five of these methods haveproven practical enough to become widely used on thefireground.

Many fire investigation agencies use mechanical or electri-cal devices for detecting the presence of flammable liquidaccelerant vapors. Although four types of these devices,sometimes referred to as “sniffers,” have proven reliable andwidely popular, each has distinctive reliability drawbacks.“Portable” versions of gas chromatographs and spectropho-tometers have been tried in the field, but have proven tounstable to be reliable.

Chemical indicators which change color in the presence ofspecific hydrocarbon compounds were tried in the field butfound impractical. Unfortunately, this method is often tooinaccurate or unspecific for fire investigation needs and is nolonger widely used.

Human olfactory testing, is the oldest and most widelypracticed accelerant detection technique. It involves theinvestigator smelling fire debris for the characteristic odorof a flammable solvent. The major drawback of this methodis that the human sense of smell becomes fatigued afterprolonged exposure to certain chemicals. However, inrecent years the introduction of accelerant detection canineshas vastly improved the reliability and performance ofolfactory analysis at fire scenes. Trained dog and handlerteams have demonstrated dramatic improvements in consis-tency, reliability, and performance in accelerant detection asverified by forensic analysis. This section examines the useof mechanical or electrical detection instruments and the useof accelerant detection canines. Although one form ofdetection may appear preferable to another, no detectionmethod is 100% reliable or accurate. Many agencies,

therefore, prefer to use more than one field detection tech-nique to improve their sampling “hit” rates.

MECHANICAL AND ELECTRONICE Q U I P M E N T

Mechanical or electrical devices for detecting the presenceof accelerant vapors fall into four major categories: catalyticcombustion detectors, photo-ionization detectors, Toguchisensor or semiconductor-based instruments, and flame ion-ization detectors. Detectors based on the catalytic combus-tion principal have traditionally been the most common andwidely used instruments for detecting the presence of accel-erants, but both photo-ionization and semiconductor-basedinstruments have become increasingly popular because oftheir improved sensitivity and selectivity. Flame ionizationdetectors are the least common of these field instruments.

Catalytic Combustion Detectors

A catalytic combustion detector consists of three basiccomponents: a pump or other means of drawing a sample ofvapor/air mixture into the instrument; a chamber containinga platinum wire coil which is part of a circuit known as a“Wheatstone Bridge”; and, a gauge for indicating thechangein the resistance of the coil. These detectors operate on thesimple electro-mechanical principal that heat and electricalresistance are related. When a sample of accelerant con-taminated vapor/air mixture is drawn into the chamber, theheat from the coil quickly oxidizes it, causing a temperaturerise. This increase in temperature increases the resistance ofthe coil, which is registered on the instrument’s gauge. Thespecific heat of combustion for a given gas or vapor ispeculiar to its molecular weight and concentration.

Most catalytic combustion detectors are calibrated to mini-mize interference from trace hydrocarbons normally presentin background air samples. Gauge markings usually corre-spond to concentrations of a known flammable gas or vaporconcentration, very often methane. Some of the moreelaborate devices produce audible warnings when the de-tected concentration excecds certain proportions of the‘calibration gas’s lower explosive limit. Since these devicesare usually calibrated against a single known flammable gasor ‘vapor as a standard, their reliability at predicting theconcentration, of other materials or mixtures of materialvapors of varying molecular weights is questionable. None-theless, most manufacturers supply conversion charts fortranslating instrument readings for the calibration standardinto equivalent concentrations of other compounds.

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Figure 3.1

Accelerant Detection Techniques

Test Method DetectionSensitivity Range

Comment

Chemical color test 1 - 5 parts per 1,000 Least specific and sensitivedetection or test method.

Catalytic combustion 1 ppm Noise from pyrolysisproducts may interfere withresults.

Photo-ionization detector 0.1 - 1 ppm Good sensitivity andselectivity. Moisture andcondensation do not affectsensitivity or selectivity,but may produce inaccurateo u t p u t .

Semiconductor or Toguchisensor-based instruments

1 - 5 ppm Dual sensor devices havegood sensitivity andselectivity, but may takemore time to setup.Hydrocarbon residueaccumulation may diminishsensitivity.

Flame ionization detector 1 - 5 ppm May yield false “positive”results.

“Portable” gaschromatograph

1 - 5 ppm Very expensive, not totallyportable, requires calibra-tion after setup, lengthyanalytic procedure.

“Portable” infaredspectrophotometry

1 - 5 ppm Needs pure sample.Impractical for field use.

O l f a c t o r y t e s t 1 ppb Human olfactory sense cansuffer from fatigue. Caninesensitivity and reliabilitydramatically superior.

Source: Lee, H. C. and Messina, D. A., Evaluation of Arson Canine Testing Program, Meriden, CT:Connecticut State Police, Forensic Science Laboratory.

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The simplicity of catalytic combustion detectors, case ofoperation, and widespread use in other emergency servicesapplications such as detecting natural gas or liquified petro-leum gas leaks have made them the most popular and widelyused type of accelerant detection instrument. Many of theseinstruments also now feature solid state electronics, digitalreadouts, print recorders, and oxygen sensors.

Photo-ionization Detectors

Photo-ionization detectors use a high frequency light sourcein the far ultraviolet range to produce ionize contaminantsin air samples entering the detector. When hydrocarbonsamples are ionized, the free electrons are attracted to acathode. The resulting change in current is amplified andregistered by a device like a meter or strip chart recorder.

These devices are usually quite sensitive and exhibit goodselectivity for hydrocarbon vapors. Photo-ionization detec-tors are considered to be up to ten times more sensitive thanflame-ionization detectors, and are much more stable. Thestability of the photo-ionization detector is a product of theenergy source and power supply. Unlike the flame-ioniza-tion detector’s hydrogen fueled flame, the battery poweredultraviolet light source produces a consistent and reliableenergy source.

Moisture and temperature extremes may affect instrumentreadings. The presence of hydrocarbon pyrolysis productsin the fire debris matrix may yield false positive readings,but perhaps no more so than other devices. An experiencedoperator can readily interpret the readings provided by theinstrument by considering the sources analyzed.

These devices are small, very portable, and easy to purge,permitting rapid sampling of suspect areas. A good photo-ionization detector instrument costs approximately $4500.

Semiconductor or Toguchi Sensor Instruments

Instruments based on the Toguchi sensor employ a semicon-ductor chip to detect the presence of hydrocarbons vapors.Elevated hydrocarbon concentrations in air infiltrate thechip’s crystalline structure, changing its conductive proper-ties. These are registered and amplified to produce an analogreading on a meter. This simple design coupled with aduplicate sensor permits background sources to be elimi-nated through calibration or comparison.

One of the leading manufacturers of semiconductor basedinstruments for accelerant detection produces a devicewhich employs dual sensor technology and multiple probesto permit the operator to zero-out background sources. Thisfacilitates easy identification of pattern boundaries whereliquid accelerants may have been poured to create trailers orfuses. Some devices also offer interchangeable sensors to

permit variable selectivity for different applications.Since hydrocarbonsarc permitted to enter the semiconductor’sstructure, they must burn-off before the device can becleared to screen a new sample. Although this takes verylittle time in most cases, it can slow down even an experi-enced investigator. Moreover, some users complain thatthese devices become contaminated over time, making itincreasingly difficult to eliminate background interference.Another serious limitation is that exposure to silicon vaporsfrom certain sources such as brake fluid and some lubricat-ing oils will destroy the sensor element.

A semiconductor-based instrument costs approximately$1200.

Flame Ionization Detectors

Flame ionization detectors mix the sample vapor/air mixturewith gaseous hydrogen and burn the mixture. The hightemperature flame produced by this combustion causes themolecules in the mixture to ionize; that is, break down intoelectrically charged chemical species. This causes the gasmixture to become electrically conductive. The degree ofionization, hence the degree of conductivity of the gasmixture, is measured using an electrometer to produce areading indicating the presence of accelerants.

This technique is capable of detecting much smaller quan-tities of accelerant than catalytic combustion detectors andreporting them much more accurately. However, the sensi-tivity of the device often works against its reliability byproducing false positive readings in the presence of pyroly-sis products of certain materials like plastics and chemicallytreated wood. Another significant drawback is the need tocarry a portable hydrogen fuel supply.

ACCELERANT DETECTION CANINES

The first accelerant detection canine program was devel-oped in 1986 through a joint program of the Bureau ofAlcohol, Tobacco, and Firearms, Connecticut State Police,Connecticut Bureau of State Fire Marshal, and New Haven(CT) State’s Attorney’s Office. Since that time, dozens ofagencies nationwide have followed suit. Still, even ardentadvocates of accelerant detection canine programs stressthat the use of the dogs is just another weapon in the fireinvestigator’s arsenal. They emphasize that training andsupport are the keys to successful use of this technique.

Training Programs

Many agencies and organizations have responded to meetthe growing demand for accelerant detection canines. How-ever, like any service, some programs and trainers are betterand more credible than others. Aside from the technicaldifferences in the training methods employed by each, the

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truest test of the credibility and performance of a caninetraining program is the results its dog/handler teams pro-duce. The field performance of any program’s graduatesshould be a significant consideration when evaluating andselecting a trainer for a new accelerant detection program.A key measure of their success is the percent of samplestaken that prove accurate. The best programs claim a 97%“hit” rate for samples identified and submitted by accelerantcanine teams for forensic analysis. Such high accuracy ratesare obtained by rigorous training and recertification and acontinual process of verification by forensic analysis.

The Connecticut State Police Canine Unit and the MaineState Police are two of the principal governmental agenciesinvolved in training accelerant detection canines for lawenforcement use. Both agencies offer training programsthroughout the year for very reasonable fees. Each hasdemonstrated consistent success and proven results with itsgraduate dog/handler teams. These agencies may be con-tacted at the following addresses and phone numbers:

Canine SectionBureau of State Fire Marshal294 Colony StreetMcriden, Connecticut 06540(203) 236-6046

Maine Criminal Justice Academy93 Silver StreetWaterville, Maine 04901(207) 873-2651 or (207) 873-4691

Support

Effective use of accelerant detection canines is a team effort.Their success is founded in cooperation between law en-forcement, fire investigation, forensic science, and criminaljustice agencies. Agencies using accelerant detection ca-nines stress that the dogs are just another tool for combattingarson. As a tool, their effectiveness is limited by the trainingand abilities of the trainer, handler, origin and cause inves-tigator, law enforcement agency, forensic laboratory, andprosecutor responsible for investigating and prosecuting thecase. The following general guidelines should help identifythe types of support required to establish and maintain aneffective accelerant detection canine program:

Dogs and handlers should be trained as ateam by competent professional canine train-ers with a proven track record training lawenforcement working dogs, preferably forspecific use as accelerant detection canines.

Accurate and contemporaneous records shouldbe maintained of all dog and handler training,fire scene experience, and laboratory results ofsamples submitted for fire scenes andrecertification or validation purposes.

A rigorous daily training and work programshould be established and followed to maintainand document the proficiency of the canine andhandler.

Accelerant detection canines should be usedprimarily to identify locations for collectingflammable or combustible liquid accelerantsamples. Every location where an animal alertsto the presence of an accelerant should besampled, and all samples should be submitted toa forensic laboratory for analysis andconfirmation.

Canines should be worked at every possibleopportunity, accidental fire scenes included, tobuild experience and confidence. When canineswork “negative” scenes, they should bereinforced afterwards with a “positive” traininghit. This ensures that the dog is ready andwilling to work every fire scene opportunity.

Accelerant detection canine team evidence andtestimony are credible and persuasive, but shouldnever be relied on too heavily to build a case forprosecution. Canine teams should avoid lettingtheir confidence in the dog’s abilities persuadethem to prosecute otherwise weak cases.

Just because a dog does not alert at a scene doesnot mean the fire was not incendiary. Dogs arenot perfect and neither are fire investigators.Every time a dog is used at a fire scene theinvestigator should have a clear understandingof what he or she expects to find or confirm.Negative and positive results alike must beevaluated carefully to determine what they meanto the fire investigation.

Successful use of this technique requires that each teammember - canine handler, fire investigator, law enforce-ment professional, forensic scientist, and prosecutor - beknowledgeable about how the dog’s use impacts their areaof expertise and how it relates to their testimony at trial.

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Chapter 4COLLECTION, PACKAGING, AND ANALYSIS OF EVIDENCE

The successful presentation of fire scene evidence of incen-diarism is often dependent upon the ability to document andverify the presence of accelerant residue in debris samples.Likewise, laboratory analysis often yields significant cluesabout the performance of fire protection features or factorscontributing to fire growth and spread. A successful fireinvestigation program uses the scientific method at the firescene and behind the scene - in the laboratory. This sectiondiscusses the procedures and equipment used in the forensicscience community to conduct laboratory analysis of firescene debris samples and photographs. The techniquesdiscussed here will have applications to accidental as well asincendiary fires.

Only the fire investigator can determine what evidenceneeds to be collected to document a particular fire,. Tech-niques used to collect, package, and store evidence forforensic analysis are dictated by the types of evidence andanalytic techniques involved. Three types of analysis arecommonly performed by forensic laboratories: accelerantidentification, comparison of evidence samples, and traceevidence examination: Each of these involves specializedanalytic techniques. In addition to these techniques, photo-graphic evidence is also a valuable tool for understandingand documenting the fire scene.

FIRE SCENE SAMPLING

Identifying what to collect and where to collect it is the mostimportant decision an investigator must make with regard toforensic analysis of evidence. Collecting insufficient evi-dence or sampling in the wrong location can severely cripplethe development of a complete fire origin and cause sce-nario. Moreover, if evidence is not collected during theinitial investigation, it may be destroyed, diluted, or alteredto the extent that it becomes unavailable, inconclusive, orinadmissible in court.

Accelerant Residue Samples

Considerable discussion has taken place in the fire investi-gation literature concerning how many accelerant residuesamples should be collected at any given fire scene. Mostlaboratories collect and analyze statistics about the workthey perform. One laboratory has suggested that a specificnumber of samples is adequate for achieving positive re-sults. Collecting more samples that the specified number,they argue; will produce only negligible results. However,the ratio of positive samples to negative samples submittedby any given fire investigator may prove little or nothingabout the investigator’s sampling techniques. In fact, good

investigation technique should include submitting samplesto confirm and refute the presence of accelerant residue. Inpractice, only the experienced fire investigator can deter-mine how many samples will be required to adequatelydocument a particular fire. Statistical evidence is importantin ensuring quality control, but it should be interpreted withcaution..

The presence of flammable or combustible liquid residue,particularly where such evidence would not normally beexpected, may be a good indicator of incendiarism. How-ever, many other cases involve the collection and analysis ofsuch debris samples to rule-out the presence of accelerantsor to identify possible flammable or combustible liquidresidues from sources other than accelerants.

The following general principles extracted from the fireinvestigation literature should apply to the selection ofd e b r i s s a m p l e s :

The collection of debris samples foridentification of accelerant residue shouldbegin as, soon as possible after fire controlefforts have been completed. ‘Fire effects,evaporation, and dilution or dispersion by firestreams all diminish the chances of collecting apositive sample where one should be present.

The best place to sample for accelerants is at theperiphery of so-called pour patterns. This isoften evidenced by a distinct interface betweenthe most heavily damaged area and the lessdamaged areas.

Absorbent materials like carpet and padding,soft woods, fabric from clothes, linens, or drapes,paper,, and soil make better samples than non-absorbent, materials like glass, tile, andconcrete.* However, some types of concreteactually, make good samples, especially whenthe sample is particularly porous and collectedbefore the potential accelerant sample can bediluted, dispersed, or evaporated.

Clean, dry absorbent cotton, sanitary napkins,or clean, dry cotton baby diapers make goodabsorbent materials for collecting flammable orcombustible liquid residues on non-porous ma-terials. Commercially available absorbent pads,such as those made of polypropylene, are unsuit-able for, this purpose because they often contain

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background contamination: These products arecommonly used in hazardous materials clean-up and are designed specifically for that pur-pose, not evidence collection.

Calcium carbonate or activated charcoal may beused to adsorb accelerant residues from con-crete. A thin layer of one of these materialsspread evenly over the surface where a residueis suspected can collect a significant quantity ofliquid. The material and a small sample of thenon-porous surface should be collected andsubmitted for analysis.3

The container in which the accelerant was trans-ported to or used at the scene is the best sourceof an accelerant residue sample.4 Even firedamaged containers often contain sufficient flam-mable or combustible liquid residue to permitanalysis. Moreover, container labels and mark-ings often provide additional valuable clues.

Trace Evidence

Trace evidence includes a very wide array of materials orclues other than accelerant samples which may indicate theidentity of a suspect(s), the motive(s), or the origin and causeof the fire. Items under this heading include:

Serological samples, e.g., blood, hair, and skin,from which blood type or a DNA “fingerprint”can be identified. This type of evidence is oftenindispensable in identifying or eliminating pos-sible arson suspects. As the scientific methodsassociated with DNA fingerprinting becomemore widely accepted and the procedure morecommon, this may also become a useful way ofidentifying fire victims.

Questioned documents, e.g., financial records,checks, letters, business papers, insurancepolicies or certificates, securities, and propertyrecords or titles. When, why, and how a docu-ment was prepared as well as what informationit contains may provide valuable clues aboutwhy a fire happened and who may be respon-sible for setting it if arson is suspected.

Latent fingerprints. Fingerprints can be a valu-able means of identifying suspects in arsoncases, as well as establishing positive identifica-tion of fire victims. Latent fingerprints mayoften be recovered from other forms of traceevidence, such as Molotov cocktails, accelerantcontainers, and failed incendiary devices. Even

small fragments of these containers or devicesmay contain sufficient information to permit apositive identification.

Device remnants, e.g., pipe parts or fragments,machine or appliance parts, wire or metalsamples, container fragments, chemical incen-diary residues, and other materials. Many foren-sic science laboratories maintain extensive ex-emplar files of materials used in the manufac-ture of incendiary and explosive devices. Evensmall fragments can often be identified usingundamaged original pieces from these files.Many other articles are extensively cataloguedand can be used to identify remnants of virtuallyany device or component. Appliance parts canoften be identified using repair, guides and main-tenance manuals. Wiring and metal, parts oftenprovide valuable clues about localized heatingor temperatures at different points in the fire ifexamined closely by a trained technician. Chemi-cal incendiaries may be manufactured from awide variety of common consumer productssuch as swimming pool disinfectant, hair gel,soap powder, brake fluid, and road flares. Oftenresidues from failed incendiaries provide valu-able clues about the ignition scenario.

Toolmarks. Most tools used for prying, lifting,and cutting leave distinctive marks. Thesemarks can be used to identify the source ofdamage to doors, windows, cabinets, and othersecure locations. Often this is important whenruling out that damage was caused by firefight-ers forcing entry for firefighting. Similarly,marks on bodies can be identified in a similarfashion. Exemplar tools and photographs areused to establish similarities between the geom-etry of the mark and individual tools. Compari-sons with tools or devices collected at the scenecan sometimes establish whether a specific toolor device was responsible for the damage.

The kinds of trace evidence collected will be most dependentupon the nature of the fire and the types of evidenceavailable. Sometimes trace evidence is disregarded in favorof collecting accelerant residue samples. This may be amistake, especially when the presence of accelerants isuncertain or the fire scenario is unclear. The best traceevidence is often that for which an explanation is notapparent. For instance, finding melted metal parts near apoint of origin may be curious but totally inexplicable at thetime they are collected. However, later analysis may laternot only provide an explanation but suggest a whole newinvestigative approach.

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A main problem in collecting trace evidence is the smallquantity of valuable trace evidence one would expect to findin a considerable volume of useless fire debris. Determiningwhat will provide information of value may be quite difficultdue to the extent of damage and the quantity of debrispresent. Destructive overhaul practices may also destroyvaluable trace evidence and produce excess debris. Sievingdebris in the field is one approach to this difficult problem.However, sieves may damage some brittle specimens, ren-dering them worthless. Although time consuming, the bestapproach is simply a thorough and systematic search of thescene.

Unlike other material evidence which may simply be pickedup or extracted and placed in a container, fingerprintsrequire highly specialized collection techniques. In mostcases where fingerprint identification is necessary, eitherspecial care must be taken to preserve the sample or thefingerprints must be “lifted” in the field by a trained techni-cian. For example, if an unbroken or defective Molotovcocktail is found at the scene, usually the investigator willwant to identify the contents to determine if it is an acceler-ant and will want to identify the perpetrator(s) who built and/or used the device. Preserving the sample for accelerantanalysis, however, will destroy the fingerprints on theoutside of the container. Therefore, either the contents mustbe decanted into an evidence container for separate analysisand the Molotov container preserved for latent fingerprintanalysis, or the prints must be lifted in the field and the entiredevice shipped to the lab for analysis. Most investigatorsprefer the former method.

Comparison Samples

Comparison samples are materials or objects which arebelieved to be nearly identical to similar accelerant debrissamples with the exception that they are not believed tocontain accelerant residues. The purpose of such samples isto identify and minimize oreliminate sources of interferencein the analysis of such samples. Examples of comparisonsamples include the following:

New, unused evidence containers. Mostevidence containers yield no chromatographicinterference. However, some types of contain-ers, like certain types of plastic bags andspecially coated containers, may give offbackground vapors which may obscurechromatographic analysis of evidence. Newtypes of containers and new lots of certaincontainer types, like plastic bags, should beperiodically submitted to the laboratory forchromatographic analysis as comparisonsamples. Likewise, collection materials maysometimes present a source of interference. Forexample, some absorbent materials for

controlling petroleum spills are unsuitable forevidence collection because they havebeen found to contain traces of contaminants.

Comparable accelerant samples. Ofteninvestigators need to identify similaritiesbetween samples of known flammable andcombustible liquids collected at the scene, fromthose found in containers or obtained from othersources near the fire scene, and flammable andcombustible liquid residues found in fire debris.Flammable and combustible liquid residues indebris samples may come from sources inherentto the scene, or may be brought to the scene fromanother source. For example, insecticides oftencontain a petroleum-based carrier. Comparingdebris samples with samples of liquids fromthese sources and with comparison samples ofmaterials similar to those present in the firedebris may be a valuable method ofdistinguishing between what was at the scenebefore the fire and what was brought to the sceneto start or spread the fire.

Comparisons are often requested by fireinvestigators when statements, evidence, orcircumstances indicate that an accelerant mayhave come from a specific source, like a suspect’sautomobile or a nearby gas station. Forensicscience analysts can occasionally discriminatebetween samples of similar materials as havingclearly different sources. However, if nodifferences are found, the strongest statementwhich can be made is that the samples may havehad a common source. This is due largely to themarketing practices of the petroleum industryand the near impossibility of accounting forevery possible source. Another possibleconclusion is that the samples belong to thesame or different classes of petroleum productsidentifiable using gas chromatographic patternrecognition. The best samples for suchcomparisons are liquid-to-liquid samples. It ismuch more difficult to determine a commonsource using liquid samples and debris samples.

Comparable material samples. It is desirable tocollect samples of materials similar to thosefound in the accelerant debris matrix that areidentical except that they contain no accelerant.These materials, such as carpet or wood trim,may often give off pyrolysis products whichpartially obscure accelerant patterns duringanalysis. A comparison sample should becollected for every questioned fire debris

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matrix.5 The same can be true of genericcollection materials such as disposable diapers.

Comparison samples can be very important to making apositive identification of a material. Whenever there is anydoubt about whether a comparison sample is needed, oneshould be collected and submitted or the laboratory shouldbe contacted.

EVIDENCE PACKAGING

Evidence packaging is important for preserving and protect-ing evidence between the time it is collected and when it canbe analyzed in the laboratory. In some cases, it may takeseveral weeks to have evidence processed by a forensicscience laboratory. The nationwide war on drugs hassignificantly increased the turnaround time for evidence atmost state and regional forensic science laboratories due tothe heavy drug-related caseload. Therefore, fire investiga-tors should take particular care in packaging and preservingevidence to maintain the quality of the sample, and preventrelease, deterioration, or contamination.

Accelerant Residue Samples

Because of the volatile nature of flammable and combustibleliquids, debris samples must be placed in vapor-tight con-tainers. According to laboratory supervisors, the best con-tainer for flammable or combustible liquid accelerant resi-due and debris samples is unused metal paint cans with tight-fitting friction lids. Laboratory personnel cite the advan-tages of the containers’ large openings in relation to overallcontainer diameter, vapor-tightness, rigid form, lightweight,durability, lack of appreciable background interferenceduring analysis, availability, and range of available sizes.Other containers have their uses as well; the container mustbe compatible with the sample and the tests or analyses to beperformed.

Samples such as clothing or textiles may be too large formetal cans. In such cases, many fire investigators havefound KapakTM bags to be a good substitute. These self-sealing bags have an exterior layer of polyester and aninterior layer of polyethylene. Many other types of plasticbags and containers may not be well-suited to use asaccelerant residue debris containers. Polyethylene plasticbags, paperbags, aluminum foil, mylar bags, and coffee canswith plastic lids are not vapor-tight with respect to flam-mable and combustible liquids. Petroleum products willpass through paper and polyethylene, and be lost to theenvironment or contaminate other samples they are pack-aged with. Other types of plastic bags, such as KapakTM ornylon, may tear if the debris sample contains sharp objectssuch a glass or nails.

Liquid samples may be placed in small glass vials withscrew-top lids, not rubber stoppers. These containers shouldthen be placed inside a metal can filled with VermiculiteTM

to prevent the vials from breaking in transit.

Some fire investigators prefer glass MasonTM jars for collect-ing and preserving evidence. The primary advantages arethe availability of these containers at hardware, variety, andfarm stores, especially in remote or rural areas away fromcentral cities. With proper protection and packaging thesecontainers can be excellent for collecting and preservingaccelerant residue samples. The screw-top vapor-tight lidswork well and the wide mouth makes it easy to insert andremove samples. Moreover, the sample remains visible,permitting inspection without opening the container. How-ever, some petroleum products and volatiles present in firedebris may degrade the jar lid’s rubber seal, allowing vaporsto escape. One proposed solution to this problem is theinsertion of a layer of aluminum foil between the jar openingand the lid.

The quantity of material needed to perform a successfulanalysis is often misunderstood. Only a relatively smallquantity of a very concentrated sample is needed. The moredilute or evaporated a sample, is the more material will berequired to perform a good analysis. Although small samplesmay be adequate under the right circumstances, in generalit is better to collect a larger as opposed to smaller sample.After all, it is often difficult to tell precisely where in a givensample area the greatest concentration of accelerant will befound. Samples should be collected at each location whereaccelerant residue is suspected. A good sized sample will filla one quart or one gallon metal can one-half to three-quartersfull. Carpet samples should be about as wide as the can isdeep, and as long as the can is round. A good carpet samplewill fully line the interior of the can. When residue isextracted from concrete, all of the absorbent material and asmall amount of concrete from the surface area where theadsorption was performed should be collected and packagedtogether. If a liquid is wiped or absorbed from another non-porous surface using a clean, dry absorbent textile material,as much residue as practical should be collected and theentire absorbent material submitted.

Trace Evidence

Trace evidence covers many different types of specimensand samples, and therefore, packaging methods vary widelyas well. The packaging technique used must be compatiblewith the type of evidence collected and the test(s) to beconducted. Many trace evidence specimens will be ana-lyzed by more than one technique.

Serological specimens and samples for latent fingerprintexamination should be sealed in brown paper bags or

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carefully wrapped in kraft paper. Air- or vapor-tight con-tainers will cause deterioration of such samples due tobacterial growth of serological specimens. Latent finger-prints will be destroyed by moisture or petroleum products.It is better to have the sample exposed to air than dissolvedby moisture or contaminated by bacteria growth.

Documents can provide valuable clues not only about whathappened but why it happened too. Questioned documentsshould be packaged in clear, protective envelopes to avoidwear and tear and protect latent fingerprints. Partiallyburned or water-soaked documents should be placed on afirm support, such as cardboard, poster board, dust pan, orcake plate, and placed in a flat box for transport to thelaboratory.6

All types of trace evidence, especially device remnants andunidentified debris, should be carefully described by theinvestigator. Extra care should be taken to give the labora-tory analyst any clues the fire investigator may have aboutthe article’s identity without presupposing any particularconclusion. Likewise, the investigator should give theanalyst a clear idea of what he or she wants to know aboutthe item, e.g., latent fingerprints, blood type, physical matchwith comparison sample, and so on.

Comparison Samples

Comparison samples should be packaged exactly the waysimilar accelerant debris or trace evidence samples arepackaged. Comparison samples are submitted for the pur-pose of minimizing or eliminating interference from sourcesother than an accelerant or identifying similarities between“knowns” and “unknowns.” To ensure the greatest degreeof reliability, the practices used for processing and preserv-ing comparison samples must be as similar to those used forthe target sample as practical.

Storage and Preservation of Evidence

With the delays in processing evidence growing in manyplaces around the country, proper storage is increasinglyimportant. Some agencies may find themselves responsiblefor evidence samples due to delays in shipment, laboratorybacklogs, or samples returned from one laboratory awaitingshipment to another laboratory. Under such circumstances,fire investigators should be prepared to store, document, andpreserve the evidence in the same manner as it would bewhile awaiting analysis at the laboratory. American Societyfor Testing and Materials standard ASTM E1492-92, Prac-tice for Receiving, Documenting, Storing and RetrievingEvidence in a Forensic Science Laboratory details thespecific practices recognized throughout the forensic sci-ence community for maintaining the chain-of-custody andpreserving evidence samples before and after forensic analysis.

FORENSIC TECHNIQUES

Modern forensic science provides valuable tools for docu-menting and verifying the findings of field investigators.Forensic science applies the principles of analytical chem-istry and physics to the identification, classification, andcomparison of evidence samples collected by fire investiga-tors for the purposes of determining the truth about fires andtheir causes. These techniques often involve complex,specialized equipment, but more importantly, they requirethe competence and professionalism of dedicated fieldinvestigators and laboratory technicians working together toobtain and analyze the evidence.

Accelerant Identification

Most flammable and combustible liquids used to acceleratethe spread of a fire are products refined from crude oil. Crudeoil and its refined products, such as gasoline, kerosene, anddiesel fuel, are complex mixtures of thousands of differentorganic compounds. These compounds are mostly hydro-carbons; that is, compounds containing only carbon andhydrogen atoms. Gas chromatography is an analyticallaboratory technique used to separate mixtures of volatileorganic compounds, and therefore, is well suited for analyz-ing petroleum products recovered from fire debris samples.

Accelerant identification in the laboratory consists of threesteps:

Sample preparation, the process by which theliquid is extracted or isolated from fire debris.

Instrumental analysis. Once isolated, a sampleis analyzed using gas chromatography (GC).GC separates components of a mixture byvolatilizing the sample into a carrier gas stream,which transports it through a column containinga fixed absorbent phase. Upon emerging fromthe column the fractions are ionized andexposed to a detector which registers therelative concentrations to permit analysis. Theconcentration results are plotted on graph paperas a function of time. This graph, called achromatogram, is interpreted by an analyst toclassify the material. GC is a good technique foranalyzing extremely small quantities ofcomplex mixtures.

Data analysis. The determination whether apetroleum product is present in the sample, andif so what the product is, is performed bycomparing the sample chromatogram with otherchromatograms of known products orcomparison samples to produce anidentification.

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Sample Preparation

The isolation and recovery of a sample is the first and mostimportant step in identifying a possible accelerant residueusing gas chromatography. There are five different methodsfor recovering petroleum products from fire debris:

Direct headspace - sampling from the vapor spacein the container above the debris sample whichmay either be heated or at room temperature.

Static head space - placing a material such asactivated charcoal in the debris which will adsorbthe volatile compounds present.

Dynamic head space - sweeping air into the con-tainer then extracting it over some material such asactivated charcoal which will adsorb the volatilecompounds present in the vapor stream.

Solvent extraction - placing a solvent such ascarbon disulfide (CS2) in the container.

Steam distillation - no longer used because it theleast sensitive and most time consuming.

Static and dynamic headspace techniques are among themost commonly used since they are very sensitive andrequire little labor. American Society of Testing andMaterials standards have been adopted to document each ofthese procedures.

ASTM E1385-90, Standard Practice for Separa-tion and Concentration of Flammable and Com-bustible Liquid Residues from Fire Debris Samplesby Steam Distillation.

ASTM E1386-90, Standard Practice for Separa-tion and Concentration of Flammable and Com-bustible Liquid Residues from Fire Debris Samplesby Solvent Extraction.

ASTM El388-90, Standard Practice for Sam-pling of Headspace Vapors from Fire DebrisSamples.

ASTM E1412-91, Standard Practice for the Sepa-ration and Concentration of Flammable and Com-bustible Liquid Residues from Fire Debris Samplesby Dynamic Headspace Concentration.

ASTM E1413-91, Standard Practice for Separa-tion and Concentration of Flammable or Combus-tible Liquid Residues from Fire Debris Samples byPassive Headspace Concentration.

Instrumental Analysis

National standards for forensic analysis of fire debris haverecently been adopted which recognize GC as the onlyacceptable means of identifying flammable or combustibleaccelerant residues. In recent years, improvements have

Table 4.1

Comparison of Gas Chromatographic Techniques

Advantages/Strengths Disadvantages/Weaknesses

Capillary column gas chromatography offers bestresolution over shortest time of current analytictechniques

When used with mass spectormetry, interference caneasily be filtered out permitting positive class specificidentification

When used with data analysis routines (patternrecognition programs), operator bias can be reduced,cost-effeciency improved, and statistical controlachieved.

Has difficulty identifying highly volatile substancesand polar solvents due to lack of generally acceptableenrichment techniques

Mass spectrometry adds to the time and cost associ-ated with processing samples, and is therefore, seldomused.

Without data interpretation, analysis is still carriedout by visual interpretation and comparison

Source: Bertsch, W., Zhang, Q.W., and Holzer, G. (Sept. 1990), “Using the the tools of chromatography, massspectormetry, and automated data processing in the detection of arson, “Journal of High ResolutionChromatography, Vol. 13, No. 9, p. 601.

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Table 4.2

Accelerant Classification Scheme

Accelerant Class and Category Approximate Boiling PointRange [°C]

E x a m p l e s

1 Light Petroleum < 1 2 0 Petroleum ethers, pocket lighter fuels,Distillates (LPD) rubber cement solvents, skelly solvents,

lacquer thinners, VM & P Natptha

2 Gasolines 50-220 All brands and grades of automotivegasoline - including gasohol, somelantern fuels

3 Medium Petroleum 60-200 Charcoal starters, paint thinners (OilDistillates (MPD) based), mineral spirits, “drycleaning”

solvents, torch fuel

4 Kerosene 90-290 No. 1 fuel oil, jet-A (aviation) fuel, insetsprays, charcoal starters

5 Heavy Petroleum 210-410. No. 2 fuel oil, diesel fuelDistillates (HPD)

0 Unclassified Variable Single compounds such as alcohols,acetone, or toluene, and xylenes,isoparaffinic mixtures, some lamp oils,camping fuels, lacquer thinners, duplicat.ing fluids, and others.

been made to this procedure to reduce interference frombackground sources within the fire debris matrix and im-prove reliability. These include the addition of mass spec-trometry and pattern recognition computer software.

To understand the application of gas chromatography to fireinvestigation, and the impact of these improvements, it isimportant to understand a little more about how a GC works.

Petroleum products contain hundreds of different organiccompounds, mostly hydrocarbons. Each hydrocarbon ischaracterized by a specific boiling point. This propertydiffers for compounds based on their size and chemicalstructure. Gas chromatography can be used to separatemixtures based on the boiling points of the components ofthe mixture. A petroleum product or isolated sample isinjected with a syringe into a heated injection port where itis instantly vaporized to the gaseous phase. The vaporizedmixture is swept into a column by an inert gas, usuallyhelium or nitrogen. As the hydrocarbons travel down thecolumn, they are separated according to boiling point. Themore volatile compounds having lower boiling points traveldown the column faster, than the high boiling point, lessvolatile compounds.

As each compound leaves the column, it passes by adetector. The most common detector type used in forensicgas chromatography is the flame ionization detector (FID)

because it is best at detecting organic compounds and isespecially sensitive to hydrocarbons. As a compound passesthrough a hydrogen flame in the detector, it is ionized. Thepresence of charged particles, ions, within an electrode gapcauses a current to pass through the gap. The current ismeasured and amplified by an electrometer, which sends asignal to a recording device, such as a mechanical chart striprecorder or a computer. The resulting chart is known as achromatogram. This chart contains many peaks, each ofwhich correspond to at least one chemical compound.Collectively the peaks form a pattern. Patterns of chromato-grams of samples isolated from fire debris are visuallycompared to patterns of chromatograms of known petro-leum products to obtain an identification.

To’ ensure reliability, repeatability, and consistency, theforensic science community has developed guidelines forconducting laboratory analyses of fire debris. These proce-dures are documented in ASTM E1387-90, Standard TestMethod for Analysis of Flammable or Combustible LiquidResidues in Extracts from Samples of Fire Debris by GasChromatography. Another standard, ASTM E1389-90Standard Practice for Cleanup of Fire Debris Sample’Extracts by Acid Stripping, covers one cleanup method toremove interfering compounds arising from the samplematrix.

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Data Analysis

Most chromatograms are still visually analyzed or “eye-balled” to ‘identify’ the material present in the sample.Although each petroleum product produces a distinctivechromatogram based on its chemical composition, back-ground volatiles found in most fire debris may cause evensimilar fire debris samples to produce different chromato-g r a m s .

Pattern recognition is the method used to identify petroleumproducts recovered from fire debris. Forensic laboratorieshave examined hundreds of commercially available petro-leum products and found their chromatographic patterns fallinto the five categories shown in Table 4.2. Because of theblending processes used to manufacture automotive gaso-line, it produces a pattern unique enough to be in a class ofits own. The other classes of products represent “cuts” offthe distillation tower at the refinery. Note that these classescontain a variety of commercial end use products. It is notpossible for the forensic science analyst to determine whatthe exact commercial end use was of a product detected ina fire debris sample,. For example, the same mediumpetroleum distillate (MPD) may, be sold commercially aseither paint thinner, mineral spirits, a dry cleaning solvent,or a charcoal lighter fluid. The fire investigator must keepin mind that a petroleum product detected in fire debris maycome from a variety of sources, some of which are inherentto the scene.

The sample preparation techniques used to recover petro-leum products from the fire debris also recover combustionand pyrolysis products from the sample matrix. The samplematrix may consist of wood, carpet, or other furnishing andbuilding materials in addition to flammable or combustibleliquid-residue. The presence of these materials may compli-cate the chromatogram to a point where the identification ofa petroleum product is not possible due to interference frompyrolysis products. In some cases, using a more selectiveand specific detector can help. One detector used for thispurpose is the mass spectrometer. Where the flame ioniza-tion detector merely detects the presence of organic com-pounds, the mass spectrometer can determine what specificchemical compound is coming out the end of the GC column.Using various computer data manipulation routines, gaschromatography/mass spectrometry (GC/MS) can some-times identify petroleum products in samples containinginterfering peaks in the GC-FID chromatogram.

GC/MS is also useful for identifying products ‘that areunusual or contain only a few chemical compounds andtherefore do not produce a distinctive pattern. One exampleis alcohol. Grain alcohol (ethanol), wood alcohol (metha-nol), and rubbing alcohol (propanol or iso-propanol) allconsist of a single chemical compound, and will produceonly one peak on a GC-FlD chromatogram. GC/MS on the

other hand, can identify that the compound is indeed, forexample, ethanol. Being volatile and water soluble, alco-hols are not likely to be found in fire debris samples. If aninvestigator thinks alcohol may have been used to set a fire,he or she should alert the laboratory analyst so the propersteps can be taken to recover and identify the material indebris samples.

Computer pattern analysis provides another useful way ofidentifying accelerants from complex chromatograms.Computers and specialized software employing complexstatistical techniques may be used to compare the samplechromatogram with othersstored in the computer’s data filesand analyze the correlation between them. This techniqueis limited, however, by the complex software required toperform the calculations and the fact that mini- or main-frame computers are required to perform the calculations.To date, computer pattern recognition has been applied toidentification of the source of oil spills, but has not beenwidely adopted for use in the analysis of data from fire debrissamples.’

After the chromatogram has been generated, it is interpreted.Five categories are used to classify flammable and combus-tible liquids. These are illustrated in Table 4.2. Fireinvestigators often request that forensic science laboratoriesidentify a specific product such as gasoline by brand orgrade. The nature of gasoline refining and marketingcurrently make this impossible. It is not practical to describea sample in terms more distinctive than these fivecategories:light petroleum distillates, gasoline, medium petroleumdistillates, kerosene, and heavy petroleum distillates.

Examination of Trace Evidence

Examination of trace evidence is conducted either to iden-tify the material or its source, or associate the item orspecimen with another sample. A vast array of techniquesis used to analyze trace evidence. Most of these techniquesinvolve the careful, detailed examination of the article orspecimen. Special equipment may be used to enhance theanalyst’s visual capabilities and produce permanent recordsor images of the observations made. The most popularinstruments for analyzing trace evidence are the magnifyingglass and stereo microscope. Scanning electron micro-scopes, metallurgical, x-ray diffraction, infrared, ultravio-let, and other techniques are also frequently employed.8

An example of the power of trace evidence examination isillustrated in the techniques employed in the investigation ofa bombing. Pipe fragments from a device may be recoveredduring on-scene investigation and shipped to the laboratoryfor examination. During examination, the analyst carefullyand systematically searches the surface for chemical resi-due. If a particle of smokeless powder is discovered,its shape, color, and texture are classified and compared with

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the characteristics of smokeless powder samples on file withthe laboratory to make an identification. The pipe fragmentsthemselves are compared with exemplars or samples ofundamaged pipe from a wide variety of manufacturers also’kept on file in the laboratory. Finally, the fragment isexamined for the presence of latent fingerprints. Any printsfound are lifted and classified. The fingerprint classificationis then compared with those on file in a national database andif a “hit” is obtained, the actual fingerprint samples arecompared.

Other types of evidence undergo similar examination pro-cesses. For example, an analysis of a questioned documentmay be conducted to discern what information it containsand determine its origin. Likewise, latent fingerprints maybe lifted from such documents. Forensic specialists knownas “questioned documents examiner” analyze the origin andpreparation of documents. Latent fingerprint examinersidentify, classify, and analyze fingerprint evidence. Toensure that both procedures produce the proper results, thedocument should be examined by the questioned documentsexaminer first. This way any damage caused during thelatent fingerprint examination will not obscure or destroythe evidence of the document’s origin or method of prepa-ration or alteration. Serological samples are chemicallyanalyzed to identify blood type, perform DNA fingerprint-ing, or determine specimen morphology for comparisonwith samples from suspects.

Comparison of Evidence Samples

Comparison samples are processed in the same manner asthe counterparts to which they will be compared. Thecollection and analytic techniques should be as similar aspossible to ensure validity and reliability.

PHOTOGRAPHIC PROCESSING ANDANALYSIS

Photographic documentation of the fire scene is perhaps themost common of all analytic techniques. The adage that “asingle picture is worth a thousand words,” is certainly truewhen documenting or analyzing a fire scene.

This section discusses the types of equipment and suppliesused to document fire scenes visually, and the application ofphotographic evidence is considered. For a detailed discus-sion of how to photograph the fire scene, see the excellentreferences on this subject in Chapter 6.

Fire Scene Photography

Without going into detail about how to take pictures of thefire scene, it is important to understand what to photograph.

Photographs should serve as a visual record of the circum-stances surrounding the origin and cause of the fire. Thephotographic record should, to the extent practical, presenta visual report of the fire.

Two general rules of thumb should apply to fire scenephotography:

‘Work from the general to the specific. Eachphotographic sequence tells a story. A good storyalways describes the setting in detail. The bestcomposite of the fire scene story is told by weavingthe details in close-ups into the larger mosaic of thefire as a whole.

‘Don‘t be afraid to take too many pictures. Pho-tographic film and processing are a lot cheaperthan a lost opportunity to clear a case. Failing todocument a key piece of evidence or documenthow it was discovered or processed can damage anotherwise credible case. Reason should prevail indeciding what to take pictures of or how many totake, but it is usually better to err on the side ofmore rather than less. Besides, there are plenty ofways to economize in the way the photographs aretaken and processed rather than simply not takingthem at all.

During the fire -- Fire scene photographs taken during thefire can be a valuable adjunct to the investigative record,especially if they can be tied to a particular point in time. Fireinvestigators can use these pictures to obtain a better under-standing of the fire’s development while it was in progress.Vehicle-mounted videotape cameras are another way ofproducing a detailed visual record of the fire while it is stillin progress. Many police agencies have recently beguninstalling these devices in large numbers to record policeactivity like traffic stops. Many of these cameras also comeequipped with time and data stamps.

Exterior -- Photographs of the outside of the buildingdocument what the firefighters themselves may have seenwhen they arrived. Smoke stains, thermal damage, andstructural collapse all document what effects the fire mayhave had on the inside, as well as the potential effects onadjacent structures. Exterior photographs should illustratethe following key features:

Property address or locationRelationship to adjacent properties or structuresCondition on each side beginning with the“front,” that being the side to which the firedepartment first respondedConditions at specific locations where smoke orfire vented or collapse occurred

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Figure 4.3

Anytown Fire DepartmentFire Investigation Unit

Photographic Log

Address: 4321 W. Broad Street Investigator: B. Dano Date/Time: 1-1-91 12:01 am

Photo No.(Roll/ Subject Exposure Flash

Exposure)Information

A/1 Exterior front (side 1) from across street, 35 mm Wide XNote: Heavy fire damage above front door f2.8 - 1/60with smoke staining and radiating vee pattern.

A/2 Exterior east side (side 2) from front porch ofadjacent dwelling. Note: Broken windows onfirst and second floors, smoke stains over 1stfloor.

50 mm Xf1.7 - 1/60

A/3 Exterior rear (side 3) from alley. Note: No 35 mm Wide Xfire damage, door forced open, windows f2.8 - 1/60broken on first floor.

A/4 Exterior - closeup rear door from back porch. 70 mm Zoom XTool marks look like FD forcible entry. f16 - 1/60

A/5 Exterior west side (side 4) from side yard of 35 mm Wide Xadjacent property. f1.7 - 1/60

A/6 Exterior - front entrance door open. Taken 50 mm Xfrom porch. Note: High heat damage and f3.5 - 1/60diagonal burn pattern.

A/7 Exterior - closeup on front door lock and 70 mm Zoom Xhardware from porch side. f16 - 1/60

Entrances -- Each entrance to the building should becarefully examined and photographed to document its con-dition at the time the fire occurred and during the incident.Close-ups of tool marks will help corroborate witness ac-counts and may aid forensic science analysts in determiningwhat tool(s) may have caused the damage. Locking andsecurity hardware should be carefully photographed todocument how the scene was secured and how it may haveaffected occupant egress.

Interior -- Photographs should document the inside begin-ning with the areas of least damage and working toward thearea of heaviest damage. This is generally the preferredinvestigative sequence as well. Photographing as you gohelps tell the story of how the fire was investigated andconfirms that proper investigative procedures were em-ployed throughout.

Photographic Log -- It is a good idea to keep a log of whatwas photographed, where it was photographed from, andhow the picture was taken. This information may becaptured textually, verbally, graphically, or by a combina-tion of these means. It is often difficult to fully understandwhat a photograph was intended to illustrate if this informa-tion was not recorded. Even properly exposed photographsare sometimes very difficult to interpret due to the nature ofthe subject. Likewise, fire scenes often produce extremelypoor photographic conditions. Where a photograph does notcome out properly, it is often helpful to know why it did not.The photographic log will also documents the sequence thephotographer used to approach the subject investigated andphotographed. Since photographs appear in time sequenceon a roll of film, this is a useful way of demonstrating thata systematic method was used to investigate and documentthe fire scene.

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Figure 4.3 details a few entries from a good written photo-graphic log. Note that it contains an identification of thephotograph as it appears on the roll; a description of what isin the picture; where it was taken; what lens, aperture, andexposure were used; and, whether or not it was taken with aflash. The same information can be read into a small taperecorder or into the microphone of a video camcorder. Manyfire investigators also produce detailed floor plans to docu-ment what was photographed and where the photographerstood while taking the picture.

Photographic Equipment and Techniques

Almost any camera is better than no camera. Taking goodpictures is more a matter of the photographer’s skill than thequality of the camera. Today more than ever, the introduc-tion of low cost high-quality photographic equipment andhigh-speed film have made fire scene photography morepractical than ever before, even for small departments andthose on tight budgets.

Cameras, Lenses, and Accessories -- Most fire investigatorsseem to prefer 35-mm single lens reflex (SLR) cameras withinterchangeable lenses. These cameras give the user controlof aperture, film speed, shutter speed, and flash. Fireinvestigation units on tight budgets, fire company officers,and inspectors have found the new generation of 35-mmautomatic cameras with fixed lenses quite useful. Many ofthese cameras come equipped with so-called data-backswhich imprint the time or date on the photographic image.Some even adjustable lenses which provide a range of focallengths from close-up to zoom. More recently, automaticsettings and features have been combined with the tradi-tional features of SLR cameras to give the photographer afull range of creative options. These cameras have madehigh-quality photographic capabilities accessible to almostall departments and make fire scene photography increas-ingly practical.

When selecting a camera for fire scene use, the fire sceneenvironment should be a prime consideration. Dust, dirt,water, and corrosive gases and vapors may all damage thecamera and accessories. Most professional SLR camerascan take this kind of abuse if they are handled with adequatecare and cleaned and maintained regularly. Lenses will beone of the most vulnerable parts of the camera, and shouldbe covered when not taking pictures. To provide protectionduring photographing, a clear or ultraviolet filter should beattached to prevent the lens’ surface from being scratched byfire debris. It is much cheaper ($15 - $20) to replace a filterthan a lens ($75 on up).

As already mentioned, fire scenes are not the best photo-graphic environments. Fire and soot blackened surfacesmake getting good contrast extremely challenging. Flashunits may be particularly susceptible to water damage Flash

units should provide adequate power to fully illuminate evenvery dark subjects.-Many camera kits come with their ownflash units, but these are usually designed for “normal’?picture taking; more powerful units may be needed for firescene work. Keeping power supplies and flash units coveredwhen not taking pictures and avoiding water spray at alltimes are generally good rules of thumb.

Many cameras now come equipped with built-in automaticwinders. Some photographers use external motor drivesand/or automatic winders to advance and rewind the film.Like other motor driven devices, motor drives and automaticwinders may be highly prone to shock and impact damage.External motor drives and automatic winders run approxi-mately $150 to $200.

A tripod or monopod makes an excellent accessory. Largeapertures and slow shutter speeds are often required due tothe poor light conditions and contrast found on the fire scene.These conditions can cause pictures to blur easily. A tripodor monopod provides an ideal support from which to shootunder these difficult conditions. A good tripod costs about $100.

Again, fire scene conditions conspire against otherwisegood photographers. Poor lighting and contrast will makea flash a necessity rather than an option. Under normallighting conditions a light meter will help the photographerdetermine the best shutter speed and aperture to use to obtaina given exposure. Most flash units require that a singleshutter speed be used in order to maintain synchronizationbetween the shutter and the flash. A flash meter will do thesame thing as a light meter except it works with a flash.Instead of reading the amount of ambient light available, aflash meter measures the amount of light reflected by thesubject under flash lighting conditions and recommends theappropriate aperture to achieve proper exposure. Good flashmeters start at approximately $120 and run into the neigh-borhood of $350.

Film -- A wider variety of film is now available. Moreover,the high speed films of today produce higher quality images.A great many options are now available to the fire investi-gator for documenting the fire scene. The photographic andfire investigation texts referenced in Chapter 6 includeextensive discussions of film speeds and types.

Most fire investigators report that they prefer 35mm colorslides for fire scene photography. Color slides have severaladvantages over color and black-and-white prints.

Cost less to processBetter image qualityAbility to produce duplicates and prints fromsame slideAbility to project images for courtroompresentations

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The single greatest drawback of slide film is that it is slightlymore expensive to produce prints from slides than fromnegatives. Since a slide is a positive image, an internegativemust be produced before a print can be made. Usually thisresults in only a slight loss of color and image quality.Although slides and prints can be produced from otherphotographic media, the duplication process can be quitecomplex. Moreover, with each step in the reproduction orduplication process, some loss of clarity or color contrastoccurs. Slides produce the best reproduction results for themoney.

Other options are available which produce better results forcertain situations. For example, print film provides thephotographer with wider latitude than slide film in terms ofexposure. Since the final product is a photographic print, anunder exposed negative can be corrected simply by exposingthe print for a longer period and vice versa. Another optionhas become available in the past several years which yieldsboth prints and slides. At least three mail-ordervendors havebegun offering dual media films which produce imagequality comparable to slides while providing the flexibilityto produce a print without having to create an internegative.

Instant photography has gone from fad to mainstream.Today, instant photography has become a popular tool forcapturing images quickly when only a single copy is re-quired. The drawbacksof most instant photography are poordepth of field, poor image quality, poor adaptability (mostof the cameras only have a single, fixed lens),, and filmexpense. However, some evidentiary purposes lend them-selves particularly well to this technique. The most popularmanufacturer of instant cameras and films has developedproducts aimed specifically at capturing macro images ofsmall objects. Moreover, they have developed services forduplicating their photographs when the need does arise.Generally this involves taking a picture of your picture undervery controlled conditions. Nonetheless, instant photogra-phy remains one of the less popular fire scene photographictechniques.

Video Camcorders -- Video camcorders havebecome one of the most popular items on fire

investigation unit wish-lists. Videotape offersseveral advantages over traditional still photo-graphs. Perhaps the most important of these is theability to capture the whole fire scene in context.Each videotape can act as a guided tour of the firescene. As lay people become more and morefamiliar with videotape in their own homes, theymay be expected to become more impressed by itas jurors when it is used to document the fire scene.

Another of videotape’s advantages may also be a weakness.Most videotape camcorders offer the ability to record soundas well as visual information. As such the accounts anddescriptions of the investigator may be captured as the scene

is processed. Consequently, fire investigators using video-tape should be very careful about what they say while the

camera is “rolling.” Preliminary conclusions and statementsabout suspects or suspicions about probable cause couldbecome part of the record. Videotape used in the preparationof an arson case can be subject to the rules ofdiscovery, andthese statements can then be used to attack the investigator’scredibility and independence.

The ability to edit and enhance videotape is another advan-tage with potential drawbacks. Editing videotape gives theinvestigator the ability to “cut to the chase,” and bypassunimportant details so long as the complete unedited versionremains accessible to the defense. Titling and captioningvideotape gives the fire investigator the ability to reinforceor clarify key points about the information on the videotapeand can be powerful tools in the use of videotape in thecourtroom. However, the videographer must be ready todemonstrate that the images presented, after editing, titling,or captioning, remains an accurate and factual representa-tion of the fire scene or subject.

Additional advantages of videotape are its ease of duplica-tion and case of presentation. Several copies can be madefrom the same original. With good duplication facilities thenumber of copies from a single original is virtually limitless.Also, an almost unlimited number of people can view thesame videotape, either individually or simultaneously de-pending on the sophistication of the broadcast capabilities.

The two most popular formats currently are ½inch VHS and8-mm. Whichever format is selected, the final productshould be compatible with the intended playback equipmentor duplication facilities should be available. The expense ofvideotape as a fire scene tool ranges from a little less than$1000 for a good camcorder to several thousand dollars foradvanced editing, titling, captioning, and broadcast capa-bilities.

Using Fire Scene Photographs

Fire scene photographs are generally taken to document theconditions found during the investigation so that they can bepreserved after the scene is destroyed, altered, or restored.Their principal use is in presenting a visual account of thefire and its effects. Recently a serious debate has emergedwithin the fire investigation community about whether ornot fire scene photographs can be used in lieu of on-sceneinvestigation to evaluate certain conditions related to a fire.9

Those who support analysis of photographs in lieu of on-scene investigation readily admit that it is a poor substitutefor on-scene investigation. It is sometimes difficult to tellwhether a photographic detail comes from the photographicprocess or was something real on the fire scene. The valueof photographs is obviously limited to that which theyspecifically portray. In many cases, this information, out ofcontext, is meaningless.

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Nevertheless, the use of photographs to analyze events afterthe fire scene investigation is complete is widely recognizedas a legitimate investigative technique. In forensic analysis,photographs are often the only record of the position orcondition of an object before it was collected or recoveredfor analysis. Consequently, the analysis of photographsshould never be dismissed out-of-hand. However, photo-analysis should never replace thorough on-scene investiga-tive efforts either.

Fire scene photographs and visual information can be pre-sented a number of different ways with dramatic appeal andeffect. The format and presentation chosen should try tosatisfy each of the following conditions:

Accuratelyrepresent the conditions as they existin the field when the image is capturedAccurately portray the relationship between thesubject and its environmentProduce adequate contrast and detail to permitall important features to be clearly discernedClearly depict the subject so it can be easilyunderstood by those who must use it

The last point is the easiest to overlook. Fire scene photog-raphers often view themselves as the primary audience fortheir pictures. However, if videotape or photographs aretaken for evidentiary purposes, many other viewers mustalso use the images. A forensic science technician maymake a positive identification of an object which is crucialto the case on a good photograph. Civil trials may developmonths or years after accidental fires are investigated. Anattorney may decide how to proceed with a defense based onthe photographic record. And a jury may decide the guilt orinnocence of a defendant on the strength of photographicevidence. Even non-evidentiary photographs are oftenviewed by many people. Keeping the subject and theviewers in mind will make a better photo or video imageregardless of the equipment used.

ENDNOTES

1. Sanderson, J.L., Ballict, C. A. and Balliet, M. A. (March1990) “Sampling Techniques for Accelerant Resi-due Analysis,” Fire and Arson Investigator, Vol.40, No. 3, p. 36.

2. Dietz, W. E. (June 1991). “Physical evidence of arson:Its recognition, collection, and packaging, “Fireand Arson Investigator, Vol. 41, No. 4, p.35.

3. Ibid., p. 35.

4. Ibid., p. 34.

5. Ibid., p. 36.

6. Ibid., p. 39.

7: Ibid.

8. Custer, R. L. P. (1991), “Fire Loss Investigation, “Section10/Chapter 1, Fire Protection Handbook, 17th ed.,Quincy, MA: National Fire Protection Associa-tion, p. 10-7.

9. Smith, D. M. (Sept. 1990), “Investigation of fire throughphotographs! Impossible?“, Fire and Arson Invest-tigator, Vol.41, No. 1,(pp. 59-60). Wagner, R. W.(March 1991) “The investigation of fire throughphotographs! Yes, impossible!“, Fire and ArsonInvestigator, Vol. 41, No. 3, (pp. 58-59) andSanders, D., ibid., (p.60).

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Chapter 5 - COMPUTER SYSTEMS

Many of the public sector pioneers of information process-ing used to rely on mainframe and minicomputers for theirinformation processing needs. While they still have theirplace, the computing power that once required a dedicatedmainframe and a staff of programmers is accessible toanyone who can afford a personal computer and learn to useavailable software packages.

Personal computers have gained widespread acceptance inthe fire investigation for managing data, writing reports,preparing diagrams of fire scenes, analyzing numerical datalike financial statements and fire statistics, preparing graph-ics, and communicating with remote computers to shareinformation or conduct research. As the number of agenciesusing computers has grown, so have the number and type ofapplications to support their needs. This section discussesspecialized applications for fire investigation, as well as thebasics of off-the-shelf software that may be useful to fireinvestigators.

HARDWARE

Before discussing the software that makes a computeroperate, it is necessary to have a basic understanding of whatconstitutes a computer system. Regardless of the type(makeor model) of computer, every system consist of five maincomponents:

Central processing unit (CPU)Random access memory (RAM)Storage device(s), e.g., disk drive, hard diskdrive, floppy disk drive, optical disk drive, tapedriveInput device(s), e.g., keyboard, mouse or otherpointing device, text or graphics scannerOutput device(s), i.e. video display terminal(VDT), printer, plotter, modem

The make, model, operating system, memory, display, andoutput devices (peripherals) must all be compatible with oneanother to operate properly. And all of these variables havesome impact on what software your computer will run.

Ideally, the decision about what hardware to use shouldcome after identifying and, defining the task or tasks forwhich the computer system will be used. The use of thecomputer will in turn establish what kind of software will berequired to perform that task. By defining criteria forperformance of these tasks, such as speed, ease of use, andprice, decisions can be made about the system to purchase- including both hardware and software.

Many agencies have already made the leap to computers. Inthese casts, care must be taken in selecting new software toensure compatibility with the system hardware already inuse. As new software comes on the market, many users findit necessary to upgrade the memory, display, or storagecapabilities of their systems to take advantage of newsoftware features.

APPLICATION PROGRAMS

Computers are far from being “thinking machines.” Actu-ally, computers themselves are quite dumb, nothing morethan a collection of inanimate parts. If computers are sodumb, how do they do such powerful things? The answer liesin the software which brings the inanimate parts to “life.”Essentially, someone else has had to do the thinking. Appli-cation programs are the answer. Unless you are a computerprogrammer, or have the budget to hire one, you probablyuse application programs for everything your computerdoes. Most application programs for personal computers fallinto one of five major categories:

Word processingDatabase managementSpreadsheetsGraphicsCommunications

As this list illustrates, these programs provide you with thetools to perform a wide variety of tasks. Most fire investi-gators will probably find the existing application programsquite capable of servicing their computing and dataprocess-ing needs. Word processing, database management, numbercrunching, drawing and graphics, and electronic communi-cations are no different for fire investigation than the sametasks in other disciplines.

Off-the-shelf application programs can be useful tools of thefire investigation trade. Like other tools, they are only aseffective as the person using them. Application programsonly instruct the computer to perform those tasks yourequest. Therefore, training and practice are required.Although you do not need to be “computer literate” to usethe most current application programs, most fire investiga-tors will find that a modest investment of time is required tobecome proficient. The emphasis on “user friendly” pro-grams for all applications has produced programs whichmost fire investigators will find useful and easy to learn anduse in a minimum of time. Moreover, the overwhelmingmajority of fire investigation computing can be performedusing the off-the-shelf application programs. For those whostill find the personal computing intimidating, low cost

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short-courses, seminars, self-instruction videocassettes, andtutorials are available.

Word Processing

Word processing or writing programs allow you to interactwith your computer to product written records and docu-ments. Modern word processing and desktop publishing(DTP) programs incorporate features formerly restricted totypesetting machines. The major advantages of word pro-cessing programs over typewriters and handwritten docu-ments are editing, appearance, and space. Word processingsoftware permits the writer to edit and modify text beforeprinting. Revisions can be incorporated without producinga whole new document. This alone is a major labor-savingadvantage. Advanced editing and formatting features, nowpart of most programs, make it easier to produce higherquality documents and publications with greater “eye-ap-peal.” Most programs now incorporate features for viewingthe document as it will appear on the printed page withoutwasting a sheet of paper. For the investigator, the appear-ance of a document can be almost as important as the contentwhen it is used to influence or convince a prosecutor or jury.Advanced formatting and typesetting features and the use ofgraphics in documents make it easier to demonstrate thelogic of arguments and reinforce the writer’s credibility.Finally, computer generated records take up far less spacethan paper documents. One floppy diskette can often storehundreds of pages of information.

The disadvantages of word processing software are rela-tively few, the most commonly cited ones being the diffi-culty learning how to use a particular system, the cost of theprogram, and cross-compatibility between different plat-forms and applications. In general, it is both possible andrelatively easy to minimize any one or more of thesedisadvantages through informed shopping. The key tofinding the right software at the right price is knowing whatyou need to do, what you want to do, and what you are willingto pay to get the job done. The more you are willing to spendthe more you will be capable of doing. Most word processingprograms retail between $250 and $500. Desktop publishingprograms anchor the upper end of the price spectrum,weighing-in at about $900. Concerns about the user-friendliness of a program and the quality of customer supportcan usually be addressed by interviewing other users or aquick survey of the popular computer-oriented media.

Database Management

A database is nothing more than a collection of informationabout a particular topic or subject. Database managementsoftware permits large amounts of data to be stored effi-ciently and allows that data to be efficiently sorted, analyzedand reported on. Moreover, many programs permit the userto use the trends and relationships among these data to

predict the course of future activity. Although most databaseprograms are somewhat more compIicated to use than wordprocessing programs and require some planning and trainingto use properly, the dividends they pay will become clear assoon as the system is put to use. Most off-the-shelf databasesoftware runs in the $200 to $500 price range. Customdesigned software for fire investigation and fire reportingcosts between $1,000 and $5,000.

An example of a database is a fire department’s collectionof information about fires and emergency responses ob-tained from fire incident reports completed by company orchief officers. Most fire investigators are probably familiarwith database programs for entering and reporting on suchfire incident data. Commercial products for this applicationabound. An excellent low-cost program is the National FireIncident Reporting System (NFIRS) software, which isavailable for the cost of materials and shipping. Copies ofthe NFIRS software can be obtained by writing the UnitedStates Fire Administration, Office of Fire Data and Analysis,16825 South Seton Avenue, Emmitsburg, Maryland 21727.

The United States Fire Administration also supports a fireinvestigation software package known as the Arson Infor-mation Management System (AIMS). AIMS is a personalcomputer database system for managing arson investigationdata. AIMS is in use by hundreds of fire investigation unitsnationwide. The profiles of arson-prone buildings aredeveloped by analyzing information about incendiary firesentered in the case file database. This information can thenbe used to assess the probability that similar buildingsentered in another database will be arson targets. Copies ofthe software are available from the Unites State Fire Admin-istration, Office of Fire Prevention and Control, 16825South Seton Avenue, Emmitsburg, Maryland 21727.

S p r e a d s h e e t s

Spreadsheets are programs for collecting and analyzingdata. Spreadsheets organize the data into tables. Thesetables consist of rows and columns. Cells are the junctionsbetween vertical columns and horizontal rows. The data ina cell represents something that column and row have incommon. The rows or columns may represent records,classes, or categories or any other piece of informationcommon to other things appearing in the same dimension(horizontal or vertical). The other dimension is used torepresent another element, class, category, or record com-mon to the same piece of information.

The value of a spreadsheet is the ability to rapidly calculateand manipulate information which is related logically ormathematically. To do this, however, the user must havesome idea what relationships logically exist between theinformation in the rows and columns. A spreadsheet simplyprovides a convenient and rational way to organize and

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Figure 5.2

Sample Fire Incident Data Spreadsheet

manipulate that information. Manipulating data usuallymeans performing logical, statistical, or arithmetic func-tions on related cells, rows, or columns. Most spreadsheetsincorporate features for illustrating these relationship graphi-cally on charts, graphs, and diagrams.

Graphics

Graphics packages include programs for producing, captur-ing, and manipulating images. These images may be linedrawings, three dimensional projections, still photographs,animation or video sequences. Graphics is perhaps the mostrapidly advancing area of all computer applications. Thegrowth of this segment is directly related to the power ofimages to illustrate abstract and complex ideas. Most fireinvestigators would probably agree that illustrating therelationship between a fire, a building and its contents, andpeople, including the occupants, witnesses, and firefightersis a complex task. This makes fire investigation an idealapplication for graphics programs. The most useful pro-grams for fire investigators are drafting or drawing programsand business graphics.

Computer-aided drafting and design (CADD) packages areexcellent programs for producing scaled line drawings of afire scene. Generally, these programs permit users toproduce very sophisticated drawings with great precision.However, many of these programs are highly specializedand require training and practice to use effectively. SimpleCADD packages begin at $200. More complex programs forproducing three dimension drawings, animated models, andfull-color renderings are at the upper end of the cost rangeat about $4000.

Business graphics programs take the graphics capabilitiesimbedded in products like spreadsheet programs severalsteps further. These programs permit the user to producepresentation quality graphics in the form of transparencies,color slides, graphic insects in word processing or DTPdocuments, and self-running slide shows on the computerscreen. Most of these programs also give the user all the toolsneeded to produce simple line drawingsbut without the samelevel of sophistication present in the output of CADDprograms. Line drawings produced with these programs areusually quite adequate for most fire investigation reports.Many of the business graphics programs also have thecapability to convert graphic images captured or producedby other programs for use in their application. A goodbusiness graphics package ranges in cost from $200 to$1000. Most programs require a pointing device like amouse, trackball, or digitizing tablet.

Computer Communications

The telecommunications revolution has followed close onthe heels of the information revolution. In fact the two -information and communication - go hand in hand. Oncecomputers were on the scene, it was only a matter of timebefore it became necessary to connect them to one anotherto exchange information electronically. Today, hardly anybusiness or agency which uses computers can escape theneed to have its computers talk to someone else’s.

“Bulletin boards” are software systems that permit users topost notices electronically. To respond to a notice, anotheruser simply identifies which notice he or she wishes toaccess, and appends the record with a new message or notice.After a time, these records are cleared to make room forothers. Many bulletin boards also offer special areas for

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users to communicate in real-time directly through theircomputers. In these applications, information is exchangedbetween the sender and receiver through the host computerwith text being directed immediately to the video displayterminals of the participants.

Specialized electronic forums for fire service, law enforce-ment, and fire safety professionals have appeared on main-stream bulletin board and electronic information exchangeservices in recent years. The most visible of these aremanaged by national fire service and law enforcementorganizations. A few individuals around the country havealso setup bulletin boards. The Building and Fire ResearchLaboratory (BFRL) at the National Institute of Standardsand Technology (NIST) operates a special interest bulletinboard at no cost other than a toll call to the suburbanWashington, D.C. area. The Fire Research Bulletin BoardService (FRBBS) has been in operation since 1986, and hasaround 200 periodic ‘users.’

FIRE MODELING SOFTWARE

A great deal of time over the past decade has been spentimproving techniques for predicting fire behavior in simplecompartment fires. As the result of these efforts, severalexcellent programs for modeling fire behavior in single andmultiple compartment fires have become widely available.Many of these programs are zone models. A zone model usesthe fundamental rules of conservation of mass and energy tocalculate the position and travel of the, hot gas layer incompartment fires. In general, these models require users tospecify the size and arrangement of compartments, thelocation and area of vents (windows, doors, mechanicalventilation, and through-penetrations), and the energy re-lease rates, i.e. heat-release-rate (HRR), for the fire(s) to bemodeled. The outputs of each model vary, but most predictthe time to certain discrete events like flashover or fatalconcentrations of specified fire gas species. Most of theavailable models are programmed to operate on computersusing the DOS operating system.

The most widely recognized source of compartment orenclosure computer fire modeling programs is the UnitedStates is the Department of Commerce’s National Instituteof Standards and Technology, Building and Fire ResearchLaboratory (NIST/BFRL) in Gaithersburg, Maryland. Someof the models which have particular application to fireinvestigation include the following:

HAZARD I - user-friendly tire hazard analysis

program

1 FRBBS can be reached at (301) 921-6302 using most commercial communi-cations. Your system should be setup for 8 bits, even parity, no stop bit (8-E-0).If you require assistance, the SYSOP (Scot Deal or Charles Arnold) can bereached at (301) 975-6891.

DETACT-T2 and DETACT-QS - predicts detectoractivation

ASET - calculates available safe egress timeCCFM (version VENTS) - multi-compartment

zone fire modelTENAB - tenability modelEXITT -exit time simulation programBREAK1 - for glass breakage predictionsFPETOOL - for fire protection engineering cal

culations

All of these models can be downloaded from the NIST/BFRL’s Fire Research Bulletin Board Service (FRBBS) bycalling (301) 921-6302. FRBBS is menu driven and walksthe new user through a sign-on and password selection forfuture access.

Many of the models listed are used to predict the outcome ofa given user-defined fire or some aspect of that fire. Thesemodels can also provide a useful way of deconstructing orreconstructing the events which led to a specific fire out-come. In the field of fire investigation, the results of a givenfire are already known. The difficult task of figuring outwhat happened requires determiningwhat was there to beginwith and how it got the way it was found. Combining theother tools of fire investigation with the power of firemodeling can be a highly effective means of ensuring thatfire cause and fire development scenarios are plausible,meaningful, and well-reasoned. Computer fire models aregood tools for helping fire investigators understand, notdetermine, what happened during a given fire.

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Chapter 6 - INFORMATION RESOURCES

A good basic library of texts, handbooks, reports, journals, and periodicals will help the fire investigator stay well-informedabout developments in the field and serve as ready references during complex investigations.

THE FIRE INVESTIGATOR’S REFERENCE LIST

The following publications are widely held to be some of thebest basic references about fire and arson investigation.Every fire investigation agency should seriously consideracquiring all of the latest of editions of each volume.

FIRE INVESTIGATOR’S REFERENCE LIST

ASTM Committee E-5 on Fire Standards (1990). Fire TestStandards, 3rd ed. Philadelphia, PA: AmericanSociety for Testing and Materials.

California District Attorney’s Association and Aetna Insur-ance, Arson Investigation and Prosecution.

Cole, L. S. (1985). Investigation of Motor Vehicle Fires,2nd ed. Novato, CA: Lee Books.

Cote, A. E., ed. (1991). Fire Protection Handbook, 17th ed.Quincy, MA: National Fire Protection Associa-tion.

DeHaan, J. D. (1990). Kirk’s Fire Investigation, 2nd ed.Englewood Cliffs, NJ: Prentice-Hall.

Dils, J. (1990). Writing Fire and Non-fire Report Narra-tives. Pasadena, CA: Jan Dils.

DiNenno, P. J!, ed. (1988). SFPE Handbook of FireProtection Engineering, Quincy, MA: NationalFire Protection Association.

International Association of Arson Investigators (1983).Selected Articles for Fire Investigators, 5th ed.Louisville, KY: IAAI.

Kodak (1977). Fire and Arson Photography, Pamphlet M-67. Rochester, NY: Eastman Kodak Co.

NFPA 921, Guide for Fire and Explosion Investigations(1992). Quincy, MA: National Fire ProtectionAssociation.

Shields, T. J. (1987). Buildings and Fire. New York:Halsted Press.

Yereance, R. A. (1987). Electrical Fire Analysis. Spring-field, IL: Charles C. Thomas.

Zulawski, D. E. and Wicklander, D. (1991). PracticalAspects of lnterview and lnterrogation. NewYork:Elsevier.

JOURNALS AND PERIODICALS

Keeping current in any complex field is a constant chal-lenge. Fortunately, several excellent magazines, periodi-cals, and journals are available which run articles of interestto the fire investigator. Many of these publications subjectpublished articles to careful editing or peer review to ensureaccuracy and integrity and many do not. The following is apartial listing of relevant fire service and fire-related publi-cations available in the United States:

AMERICAN FIRE JOURNAL9072 E. Artesia Boulevard, Suite 7Bellflower, CA 90706

BUILDING OFFICIAL AND CODE ADMINISTRATORBOCA International, Inc.4051 W. Flossmoor Road,Country Club Hills, IL 60478

BUILDING STANDARDSInternational Conference of Building Officials5360 S. Workman Mill RoadWhittier, CA 90601

CALIFORNIA FIREMAN, THECalifornia State Firemen’s Association, Inc.3246 Ramos CircleSacramento, CA 95827

CALIFORNIA STATE FIRE MARSHAL’S NEWSSpecial Services Division7171 Bowling Drive, Suite 600Sacramento, CA 95823

CHIEF FIRE EXECUTIVEPTN Publishing Company445 Broad Hollow Road, #21Melville, NY 11747

27

DISPATCH1325 Pennsylvania Avenue NWWashington, DC 20004

INTERNATIONAL ASSOCIATION OFFIREFIGHTERS MAGAZINE

1750 New York Avenue NWWashington, DC 20006

FIRE AND ARSON INVESTIGATOR, THEInternational Association of Arson lnvestigatorsP.O. Box 91119Louisville, KY 40291

INTERNATIONAL CONNECTIONSInternational. Association of Fire Chiefs4025 Fair Ridge RoadFairfax, VA 22033

FIRE CHIEFCommunication Channels, Inc.307 N. Michigan AvenueChicago, IL 60601

MINNESOTA FIRE CHIEF3 17 Owasso Boulevard SouthSt. Paul, MN 55 113

FIRE CODE JOURNAL NATION’S CITIES WEEKLYInternational Fire Code Institute National League of Cities5360 S. Workman Mill Road 1301 Pennsylvania Avenue NWWhittier, CA 90601 Washington, DC 20004

FIRE CONTROL DIGEST3918 Prosperity Avenue, Suite 3 18Fairfax, VA 22031

FIRE ENGINEERINGPark 80 WestPlaza Two, 7th FloorSaddle Brook, NJ 07662

NFPA JOURNALNational Fire Protection Association1 Batterymarch ParkP.O. Box 9101Quincy, MA 02269

FIREFIGHTER’S NEWS424 S. Rehobeth RoadP.O. Box 165Milford, DE 19963

OREGON FIRE SERVICE GATED WYEOregon State Fire Marshal’s Office4760 Portland Road NESalem, OR 97305

FIREHOUSEPTN Publishing Company445 Broad Hollow RoadMelville, NY 11747

PUBLIC FIRE EDUCATION DIGESTOklahoma State University2004 S. Deerborn CircleColumbia, MO 65203

SIZE-UP

FIRE TECHNOLOGYNational Fire Protection Association1 Batterymarch ParkP.O. Box 9101Quincy, MA 02269

New York State Association of Fire Chiefs1670 Columbia TurnpikeCastleton, NY 12033

IAFC ON-SCENEInternational Association of Fire Chiefs4025 Fair Ridge RoadFairfax, VA 22033

SPEAKING OF FIREInternational Fire Service Training AssociationFire Protection PublicationsOklahoma State UniversityStillwater, OK 74078

THE VOICE

INDUSTRIAL FIRE WORLD208-C Southwest Parkway EastCollege Station, TX 77842

International Society of Fire Service Instructors30 Main StreetAshland, MA 01721

28

PROCEEDINGS

Much of the important work done at the frontier of firescience does not appear in the better known and moremainstream fire protection publications. Most academicconferences and technical symposiums do, however, pub-lish documents such as proceedings. These publicationsserve as conduits for the papers presented at these meetingsand conferences. Many of these meetings convene at regularintervals, others are far more adhoc, occurring only once orperiodically but irregularly. The annual National ArsonForum meetings sponsored by the Insurance Committee forArson Control and the Worcester Polytechnic Institutesponsored Conference on Fire Safety Design in the 21stCentury are examples of such symposiums.

ELECTRONIC INFORMATION SERVICES

Chapter 5 contains information about several electronicinformation services of particular interest to fire investiga-tors. Many of the mainstream information services giveusers the ability to set up clipping files newspaper and wireservice articles about topics of interest by using keywords tosearch the text of each story as it appears on the network.This can be a particularly efficient way of gaining up-to-dateinformation about emerging trends in the field or significantevents around the nation or the world.

Specialized Electronic Reference Sources

Many libraries have begun providing access to specializedelectronic reference sources, occasionally charging a smallfee to cover their on-line charges. Some of the moresophisticated services give users up-to-date access to legaldecisions, law review articles, scientific and technical jour-nals, social science abstracts, medical journals, patent andtrademark files, and dissertation abstracts. In fact, mostmajor reference sources in print have begun to appear inelectronic versions.

Fire Service Bulletin Boards

In recent years, fire-oriented bulletin board services havebegun to emerge. The lnternational Association of FireChiefs and the National Volunteer Fire Council operate twosuch services. The IAFC information service, ICHIEFS,operates as a special interest forum on another on-lineservice called ConnectTM . FireWatch, the NVFC forum,operates as stand-alone system from a computer located inColorado. As computer technology becomes increasinglyubiquitous one can only expect the number of fire-relatedelectronic information services to expand as well. Contactsare as follows:

ICHIEFSKen WestlundNational Volunteer Fire Council1422 East 110th PlaceNorthglen, Colorado 80233(303) 452-9992

FireWatchAnn Swinglnternational Association of Fire Chiefs4025 Fair Ridge RoadFairfax, Virginia 22033(703) 273-0911

UNITED STATES FIREADMINISTRATION

PUBLICATIONS

The following United States Fire Administration publica-tions provide information useful to fire and arson investiga-tors. A catalog containing all United States Fire Adminis-tration publications, titled Resources on Fire (FA-102), isavailable by contacting the United States Fire Administra-tion, 16825 South Seton Avenue, Emmitsburg, Maryland21727, (301) 447-1000.

Fire and Arson Investigator’s Field Index Directory (FA-91) -This publication serves as a compendium of expert contactsin federal agencies, government and private research labo-ratories, codes and standards organizations, trade associa-tions, product manufacturers and distributors, insurancecompanies and organizations, law enforcement agenciesand organizations, and other valuable contacts for technicalinformation and resources for fire and arson investigatorshandling complex cases.

Arson Resource Directory (FA-74) - This directory pro-vides a comprehensive listing and explanation of the roles ofthe various organizations and agencies across the nationinvolved in the fight to control arson. It includes names andcontact information for county and metropolitan fire andarson investigation units, state fire marshals offices, statetraining organizations, National Fire Incident Reportingsystem coordinators, federal agencies, and other organiza-tions such as the Federal Arson Task Force and InternationalAssociation of Arson Investigators, and other fire serviceand insurance organizations.

Arson Control Directory - This directory is producedannually through a cooperative agreement between theUnited States Fire Administration, the lnsurance Committeefor Arson Control, National Association of State Fire Mar-shals, and the lnternational Association of Arson Investiga-tors working through the National Arson Forum. It details

29

the people, groups, and organizations working to reduce theincidence of arson in the United States.

Public Fire Education Today: Fire Service ProgramsAcross America (FA-98) - This publication identifies anddescribes successful public fire education programs in all 50states and the District of Columbia. Several good examplesof anti-arson and juvenile firesetter programs are included inthe cases presented.

Rural Arson Control (FA-87) - This study report outlinesthe difficulties confronting rural communities in the fightagainst arson and recommends solutions to help these com-munities win the war against incendiarism.

Establishing an Arson Strike Force (FA-88) - This reportdescribes the Arson Strike Force concept for investigatingfires and prosecuting the crime of arson. This model hasproven to be one of the most successful programs forcombatting arson. The report outlines how to establish andadminister and arson strike force in your community.

Arson Prosecution: Issues and strategies (FA-78) - Thisreport describes the recommended methods for successfullydeveloping and prosecuting arson cases. It details the rolesof prosecutors, eyewitnesses, expert witnesses, investiga-tors, and different types of evidence and emphasizes how topresent each element of the prosecution to build a credibleand convincing case.

Preadolescent Firesetter Handbook (3 volumes) (FA-80,FA-82 and FA-83) - These manuals present an overviewof juvenile firesetter behavior and outline successful coun-seling and intervention programs and strategies for threedifferent age groups, 0-7, 7-13, and 14-18. Sample interviewand evaluation forms are provided to illustrate key concepts.And contacts are provided for existing programs in commu-nities nationwide.

Special Report - Arson in America: A Profile of 1989NFIRS - This report examines the scope of the incendiaryfire problem in America through an analysis of National Fireincident Reporting System (NFIRS) data for calendar year1989. NFIRS data is based on reports collected from over10,000 fire departments in 40 states, and 27 metropolitanareas which cooperate in the National Fire Incident Report-ing System.

A View of Management in Fire Investigation Units (FA-93) - Particular management practices from several localfire investigation units are highlighted. Factors affecting thecurrent state of fire investigation are described, includingthe trend away from joint police and fire investigation teams,the impact of drug wars on the quantity and danger ofinvestigations, the need for management training for inves-tigation managers, and inadequate data collection and appli-cation.

In addition to these publications, the United States FireAdministration maintains an Arson Resource Center in theNational Emergency Training Center Learning ResourcesCenter. Expert technical reference librarians are on-call toassist local fire investigations in finding information andspecific fire and arson investigation topics. The ArsonResource Center can be reached by calling toll-free (800)638-1821.

30

BIBLIOGRAPHY

Chapter 2 - BASIC TOOLS AND Telephone interview with Richard Motsinger, Pragmatics,

EQUIPMENTInc., August 19, 1992. Telephone interviews with MichaelHiggins, Laboratory Instrument Services, August 19, 1992

Ayers, J. H., and associates (May 1983). The Fire Investi-and September 1, 1992.

gation Van and Equipment, National Fire Academy Fire/Arson Investigation Research Paper. Emmitsburg, MD:

Telephone interviews with Sergeant James R. Butterworth,

United States Fire Administration.Connecticut State Police, July 1989.

Wittig, C. (March 1991). “Hazards for the Fire lnvestiga-tor,” Fire and Arson Investigator, Vol. 4 1, No. 3, pp. 22-

Chapter 4 - COLLECTION, PACKAGING,

23. AND ANALYSIS OF EVIDENCE

Zilke, F. and Wachowiak, M. “The Value of Photographyin a Small Fire Department,” National Fire and Arson Alford, C. and associates (May 1983). Understanding the

Report, Vol. 8, No. 5, p. 6, 11. Gas Chromatograph, National Fire Academy Fire/ArsonInvestigation Research Paper. Emmitsburg, MD: UnitedStates Fire Administration.

Chapter 3 - ACCELERANT DETECTIONBertsch, W., Zhang, Q. W., and Holzer, G. (Sept. 1990).

Berluti, A. F. (Dec. 1990). “Arson Investigation:Connecticut’s Canines,” Police Chief, pp. 39-45.

“Using the Tools of Chromatography, Mass Spectrom-etry, and Automated Data Processing in the Detection orArson,” Journal of High Resolution Chromatography,

Berluti, A. F. (June 1989). “Sniffing Through the Ashes,”Vol. 13, pp. 597-604.

Fire and Arson Investigator, Vol 39, No. 4 (pp. 31-35).Byron, M. M. (Dec. 1990). “Adequate Sampling of Fire

Byron, M. M. (1982). “Three Commonly Used AccelerantScenes,” Fire and Arson Investigator, Vol. 41, No. 2, pp.

Detectors,” National Fire and Arson Report, Vol. 1,48-49.

No. 2, pp. 6, 14.Byron, M. M. (Sept. 1989). “Inadequate Review of Field

Campbell, D. H. “Is This Sniffer Here to Stay?“, NationalData,” Fire and Arson Investigator, Vol. 40, No. 1, pp.

Fire and Arson Report, Vol. 8, No. 5, p. 7.61-62.

Connecticut State Police (Aug. 1988). Canine AccelerantChasteen, C. E. (1992). Guide to the Collection, Packaging,

Detection Program. Meriden, CT: Connecticut StateSubmission, and Analysis of Evidence from Suspicious

Police.Fires. Tallahassee, FL: Division of State Fire Marshal,Bureau of Fire and Arson Laboratory.

Custer, R. L. P. (1991). “Fire Loss Investigation,” in FireProtection Handbook, 17th ed., Cote, A. E., ed. Quincy,

“Cold Hands, Bright Snow, Dead Batteries: Challenges of

MA: National Fire Protection Association.Cold-Weather Photography,” Fire and Arson Investiga-tor, Vol. 40, No. 2, (Sept. 1989), p. 12.

Dorriety, J. K. (June 1991). “Accelerant Detector Dogs areValuable Investigation Tools,” Fire Chief, Vol. 35,

Dietz, W. R. (June 1991). “Physical Evidence of Arson: Its

No. 6, p. 50.Recognition, Collection and Packaging,” Fire and ArsonInvestigator, Vol,. 41, No. 4, pp. 33-39.

Meyer, R. E. (Oct.-Dec. 1981). “Evaluation of ThreeCommonly Used Hydrocarbon Detectors,” Fire and Ar-

Eaton, T. E. (March 1990). “Fire Transfer,” Fire and Arson

son Investigator, Vol. 32, No. 2, pp. 35-38.Investigator, Vol. 40, No. 3, pp. 42-48.

Pragmatics, Inc. (n.d.). Operation and Applications of theGalvin, M. and Toscano, J. P. (Dec. 1990). “The New Fire

Model 653 MkII “Serviceman Surveyor” and ModelsTriangle: Putting the Prosecutor on the Team,” Police

920/620 “Fire Investigators”Chief, pp. 50-52.

31

Henderson, R. W. (1989). “A Simple Introduction to Gas Thompson, V. A. (Sept. 1989). “Slides, Color Prints orChromatography, “National Fire and Arson Report, Vol. Color Negatives,” Fire and Arson Investigator, Vol. 40,7, No. 3, pp. 3, 14. No. 1, p. 48.

International Association of Arson Investigators ForensicScience Committee (June 1991). “Standard Test Methodfor: Flammable or Combustible Liquid Residues in Ex-tracts from Samples of Fire Debris by Gas Chromatogra-phy,” Fire and Arson Investigator, Vol. 41, No. 4, pp. 51-55.

international Association of Arson Investigators ForensicScience Committee (Dec. 1990). “Forensic ScienceCommittee Position on Comparison Samples,” Fire andArson Investigator, Vol. 41, No. 2, pp. 50-51.

Lentini, J. J. (March 1991). “ASTM Adopts Fire DebrisAnalysis Standards,” Fire and Arson Investigator, Vol.41, No. 3, p. 16.

Lentini, J. J. (June 1989). “Control Samples, A Reply,” Fireand Arson Investigator, Vol. 39, No. 4, pp. 39-40.

Meal, L. (Sept. 1989). “An Alternative to Gas Chromatog-raphy in the Analysis of Fire Debris,” Fire and ArsonInvestigator, Vol. 39, No. 1, pp. 55-56.

Nowicki, J. (Sept. 1990). “An accelerant ClassificationScheme Based on Analysis by Gas Chromatography/Mass Spectrometry (GC-MS),” Journal of Forensic Sci-ences, Vol 35, No. 5, pp. 1064-1086.

O’Donnell, J. F. (Sept. 1990). “Accelerant Residue Analysisby a Combined Solvent Extraction-Heated HeadspaceTechnique,” Fire and Arson Investigator, Vol. 41, No. 1,pp. 4-5.

O’Donnell, J. F. (June 1989), “Interferences from Back-grounds in Accelerant Residue Analysis,” Fire and ArsonInvestigator, Vol. 39, No. 4, pp. 25-27.

Posey, E. P. (June 1990). “Attention IAAI Members, DoYou Know About ASTM’s E-30 Committee on ForensicSciences?”, Fire and Arson Investigator, Vol. 40, No. 4,pp. 52-53.

Sanders, D. (March 1991). “The Investigation of FiresThrough Photographs,” Fire and Arson Investigator,Vol. 41, No. 3, p. 60.

Sanderson, J. L., Balliet C. A, and Balliet, M. A. (March1990). “Sampling Techniques for Accelerant ResidueAnalysis,” Fire and Arson Investigator, Vol. 40, No. 3,pp. 35-40.

Tsaroom, S, Elkayam, R., and Natayan, S. (March 1990).“Evaporation of Gasoline and Kerosene from Polyethyl-ene Containers,” Fire and Arson Investigator, Vol. 40,No. 3, pp. 21-23.

Wagner, R. W. (March 1991). “The Investigation of FireThrough Photographs! Yes, Impossible!”, Fire andArson Investigator, Vol. 41, No. 3, pp. 58-59.

Waters, L. V. (March 1991). “Adequate Analysis of Labo-ratory Data,” Fire and Arson Investigator, Vol. 41, No.3, pp. 61-62.

Chapter 5 - COMPUTER SYSTEMS

Beering, P. S. (Feb. 1992). “High-Tech Hunting and Gath-ering: Using Computers in Fire Investigations,” Firehouse,pp. 52-54.

Beyler, C. R. (1991). “Introduction to Fire Modeling,” inFire Protection Handbook, 17th ed., Cote, A. E., ed.Quincy, MA: National Fire Protection Association.

Bukowski, R. W. (March 1992). “Analysisof the HappylandSocial Club Fire with HAZARD I,” Fire and ArsonInvestigator, Vol. 42., No. 3, pp. 36-47.

Clarke, F. B. (1991). “Fire Hazard Assessment,” in FireProtection Handbook, 17th ed., Cote, A. E., ed. Quincy,MA: National Fire Protection Association.

Daugenti, J., and associates (May 1982). The Evaluation ofComputers in Arson Investigation, National Fire Acad-emy Fire/Arson Research Paper. Emmitsburg, MD:United States Fire Administration.

DiNenno, P. (1991). “The Future of Fire Modeling,“in FireProtection Handbook, 17th ed., Cote, A. E., ed. Quincy,MA: National Fire Protection Association.

Fire Research Bulletin Board Service (FRBBS), electronicinformation service. Gaithersburg, MD: National Insti-tute of Standards and Technology, Building and FireResearch Laboratory.

Hall, J. R., Jr. (1991). “Use of Fire Loss Information,” inFire Protection Handbook, 17th ed., Cote, A. E., ed.Quincy, MA: National Fire Protection Association.

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Nelson, H. E. (1991). “Application of Fire Growth Modelsto Fire Protection Problems,” in Fire Protection Hand-book, 17th ed., Cote, A. E., ed. Quincy, MA: NationalFire Protection Association’.

Nelson, H. E. (July 1989). “Science in Action: An Engineer-ing View of the Fire at the First Interstate Bank Building,”Fire Journal, Vol. 83, No. 4, pp. 28-34.

“New Computer Application for Investigators,” NationalFire and Arson Report, Vol. 8, No. 2, p. 6.

Perroni, C. A. (July 1989). “Investigating Fires the Scien-tific Way,” Fire Journal, Vol. 83, No. 4, pp. 24-27.

Peterson, C. E. (1991). “Collecting Fire Data,” in FireProtection Handbook, 17th ed., Cote; A. E., ed. Quincy,MA: National Fire Protection Association.

Walton, W. D. and Budnick, E. K. (I 991). “DeterministicFire Models,” in Fire Protection Handbook, 17th ed.,Cote, A. E., ed. Quincy, MA: National Fire ProtectionAssociation.

Watts, J. M., Jr. (1991). “Microcomputer Applications inFire Protection,” in Fire Protection Handbook, 17th ed.,Cote, A. E., ed. Quincy, MA: National Fire ProtectionAssociation.

33

APPENDIX AFIRE INVESTIGATION TOOLS AND EQUIPMENT LISTS

HAND TOOLS Screwdriver(s)Bit driver with assorted bits

Chisels Phillips headCold chisel(s) Straight bladeWood chisel(s) Screws, nails, tacks, staples

Crowbar/prybar WrenchesCutter(s), cutting tools Adjustable

Bolt cutters Open-end or boxCarpet cutters PipePipe cutterPocket knife EVIDENCE TOOLS AND EQUIPMENTRazor bladesTin snips Brush(es)Utility knife

Drill with wood and metal bitsContainers, packaging materials

Cardboard boxes, assorted sizesElectrician’s tools

Circuit continuity testerDocument protector(s)Envelopes, kraft paper or tyvekTM, assorted sizes

Electrical tape Evidence tape (tamper indicating)Fuse puller Glass jars w/ screw-top lids, assorted sizesGround fault/phase tester Glass vials w/ screw-top lidsVolt/Ohm/Amp meter Kraft paperWire cutters Masking tapeWire gauge Wire stripper Paper bags

Hammers Plastic (polyester, nylon, or KapakTM) bags,Ballpeen heavy duty (+3-mil)Claw Steel paint cans w/ friction lids, assorted sizes

Hand axe/hatchet StringHand trowel Transparent or cellophane tapeLevel (torpedo and bar) VermiculiteMagnet Drawing equipmentMagnetic compassMeasuring tools

Compass (drafting)Drafting templates, architectural

Folding rule Pens, pencilsMeasuring wheel ProtractorRuler (12-in, 14-in, 18-in) Scale, architecturalTape (25-ft, 50-ft, 100-ft) Scale, engineering

Paint brush(es) Straight edgePliers Sketch pads, quadrille ruled

Lineman’s Fingerprint kitNeedle-nose Latex rubber glovesSidecutting Magnifying glassSlip-lock Marking equipmentVise-GripTM

Evidence tags/formsPlumb bob Marking pens, indelible inkPutty knife/scraper(s) Scribe, etching toolSaws Measuring equipment

Crosscut Magnetic compassHack Scale or balanceKeyhole Range finderScroll Meters

34

BarometerCombustible gas/vapor detectorThermometer, dry bulbThermometer, wet bulbVelometer

pHNotebooksRecording equipment, sound

Blank cassette tapesTape recorder

Sample collection equipmentActivated charcoalBlotter stripsCotton-tipped swabsCotton baby diapers, clean, unusedDental toolsDisposable sterile pipets with suction bulbsDust pansEye dropperForcepsScalpelSifting screens or sieveSyringesTongsTweezers

UV (black) light

PHOTOGRAPHIC AND VIDEOEQUIPMENT

Batteries, spareCameraFlash

Camera35 mm automatic35-mm SLRInstant

Film, spareFlash attachmentInstant camera macro attachmentLenses

70-200 mm zoom28-70 mm zoom50 mm

MeterFlashLightMotor winder

Photographic backgroundPhotographic flags/markersPhotographic logsPhotographic rulerProtective carrying casesTripodVideotape boom microphoneVideotape lighting attachmentVideocassettes, blank, spare

PERSONAL PROTECTIVE EQUIPMENT

Ballistic vestBrush firefighting coatBrush firefighting pantsBoots, steel toe/shank safetyChemical splash protective coverallsCoverallsDust mask(s)Filter mask respiratorFirefighter’s bootsFirefighter’s glovesFirefighter’s turnout coatFirefighter’s turnout pantsGoggles/safety glassesHardhatLaw enforcement equipment

Handcuffs/caseHandgun, holster, ammunitionGun cleaning kit

NomexTM/PBI hoodRespirator filters, organic vapor/acid gas/HEPASelf-contained breathing apparatusSpare SCBA bottle(s)Structural firefighter’s helmetSuspendersWork gloves

COMMUNICATION EQUIPMENT

Cellular telephoneFacsimile machine

CellularOffice

Portable radioPager

RadioTelephone

Portable computer w/ modemPublic address system

VEHICLE EQUIPMENT

AC/DC chargerFirst aid kitFlood lightsFusees/light sticksJumper cablesMobile RadioPortable fire extinguisherPublic address systemReflective markersSiren

35

Spot light(s)Warning lights

MISCELLANEOUS TOOLS AND EQUIPMENT

Barricade tapeBroom(s)BucketsClaw toolCleaning ragsEntrenching toolExtension cordsFlashlightsHand cleanerHand lanternsHydrant wrenchLadder, extensionLadder, stepLight standsPickPortable generatorPortable lightsRopeShovel, chisel pointShovel, scoopShovel, square headSpadeSqueegeeTarps/salvage covers

36

APPENDIX BGLOSSARY OF FORENSIC SCIENCE TERMS

Source: International Association of Arson Investigators Forensic Science Committee (Dec. 1989), “Glossary of TermsRelated to Chemical and Instrumental Analysis of Fire Debris,” Fire and Arson Investigator, Vol. 40, No. 2, (pp. 25-34).

-A-

Absorption: 1) A mechanical phenomenon wherein onesubstance penetrates into the inner structure of another, as inabsorbent cotton or a sponge. 2) An optical phenomenonwherein atoms or molecules block or attenuate the transmis-sion of a beam of electromagnetic radiation.

Accelerant: Any material used to initiate or promote thespread of a fire. The most common accelerants are flam-mable or combustible liquids. Whether a substance is anaccelerant depends on its chemical structure, but on its use.

Acetone: The simplest ketone. A highly flammable, watersoluble solvent. Flash point of 0° F. Explosive limits of 2.6%to 12.8%.

Adsorption: The adherence of atoms, ions, or molecules ofa gas or liquid to the surface of another substance. Finelydivided or microporous materials having a large activesurface area, activated carbon, activated alumina and silicagel.

Alcohol: An organic compound having a hydroxyl (-OH)group attached. The lower molecular weight alcohols,methanol (CH3OH), ethanol (C2H5OH), and propanol(C3H7OH), are water soluble.

Aliphatic: One of the main groups of hydrocarbons charac-terized by the straight or branched chain arrangement ofconstituent atoms. Aliphatic hydrocarbons belong to threesubgroups: (1) alkanes or paraffins, all of which are satu-rated and comparatively unreactive, (2) the alkenes oralkadienes which are unsaturated (containing double [C=C]bonds) and more reactive, and (3) alkynes, such as acetylene(which contain a triple [C=C] bond).

Alkane: An aliphatic hydrocarbon having the chemicalformula CnH2n+2. A normal alkane, or n-alkane is onewhich does not have a branched carbon backbone. Anisoalkane has a branched, rather than a straight chain, carbonbackbone. Alkanes are also known as paraffins. Thesimplest alkanes are named as follows:

CH4 - methane C8H18 - octaneC6H14 - hexane . C4H10 - butaneC2H6 - ethane C9H20 - nonaneC7H16 - heptane C5H12 - pentaneC3H8 - propane C10H22 - decane

Alkene: A straight chain, unsaturated compound of theolefin series which has the generic formula CnH2n, havingat least one double [C=C] bond. (See Aliphatic).

Alkyl Group: A functional group having the formulaCnH2n+l which may be attached to certain elements suchas lead, silicon, or to other organic chemicals.

Alkyne: An unsaturated aliphatic hydrocarbon character-ized by the presence of a triple [C=C] bond. The genericformula for an alkyne is CnH2n-2. The most importantmember of this group is acetylene, HCCH, the first memberof the series.

Alloy: A solid or liquid mixture of two or more metals, orof one or more metals with certain nonmetallic elements, asin brass, bronze, or carbon steel.

Ambient: Pre-existing or normal environment.

Aromatic: An organic compound having as part of itsstructure a benzene ring. (See Benzene). The term “aro-matic” as used in the fragrance industry is used to describeessential oils, which are not necessarily aromatic in thechemical sense.

Arson: The crime of intentionally setting fire to a buildingor other property. This is a legal definition which may varydepending on the laws of a specific state.

Atom: The smallest unit of an element which still retains thechemical characteristics of that element. An atom is madeup of protons and neutrons in a nucleus surrounded byelectrons. A molecule of water (H2O) consists of two atomsof hydrogen and one atom of oxygen.

Atomic Absorption: An analytical technique, used todetermine the elemental composition and the concentrationof many metals and other inorganic elements. The materialbeing analyzed, generally in solution, is atomized, or brokenup into individual atoms, usually by the action of extremeheat in a flame or small furnace. The ability of the atomizedmaterial to absorb characteristic wavelengths of visible orultraviolet light is then measured using a spectrophotometer.

Atomize: 1) To break into discrete atoms, usually by theapplication of extreme heat, as in atomic absorption. 2) Tobreak a liquid into tiny droplets, as occurs in fuel injectedengines or in the production of aerosol sprays.

37

Attenuation: An adjustment of the signal amplifier re-sponse which results in the reduction of the electronic signal.

Azeotrope: A mixture of two or more compounds which hasa constant boiling point. The composition of the vapor abovethe azeotropic mixture has the same relative concentrationsof compounds as does the boiling liquid. Azeotropic mix-tures cannot be separated by fractional distillation.

-B-

Benzene: A hexagonal organic molecule having a carbonatom at each point of the hexagon, and a hydrogen atomattached to each carbon atom. Molecules which contain abenzene ring are known as aromatic. Benzene boils at 80° C,and has a flash point of 12° F(-11° C). The explosive limitsare 1.5% to 8% by volume in air.

BTU: British Thermal Unit. The amount of heat energyrequired to raise the temperature of one pound of water onedegree Fahrenheit. This the accepted standard for thecomparison of heating values of different fuels. One BTUequals 252 calories.

Burning: Normal combustion in which the oxidant ismolecular oxygen.

Burning Rate: The rate at which combustion proceedsacross a fuel. A specialized use of this term describes the rateat which the surface of a pool of burning liquid recedes. Forgasoline, this rate is reported to be approximately 1/4 inchper minute.

Butane: A fuel gas having the formula C2H10. A constituentof LP gas. One pound of liquid butane produces 6.4 cubicfeet of gas. One gallon of liquid butane weighs 4.87 poundsand produces 31 cubic feet of gas. One cubic foot of butanegas produces 3266 BTU’s.

-C-

Calorie: The amount of energy required to raise thetemperature of one gram of water one degree Centigrade.One calorie equals 0.004 BTU’s One BTU equals 252calories.

Capillary: A narrow boreglass tube. Capillary column gaschromatography employs glass tubes having an inside diam-eter of approximately .2 to .5 millimeters and a length of 3to 300 meters. The walls of a capillary column are coatedwith an adsorbent or adsorbents medium (a liquid phase inwhich the sample dissolves).

Carbon: The element upon which all organic molecules arebased. Carbon has an atomic weight of 12.00, and occurselementally in these forms: diamond, graphite, and amor-phous carbon such as coal or carbon black.

Carbon Dioxide: A molecule consisting of one atom ofcarbon and two atoms of oxygen which is a major combus-tion product of the burning of organic materials. Carbondioxide (CO,) is the result of complete combustion ofcarbon. In the gaseous form, CO, is used as a fire extin;guisher. In the solid form, CO, is known as dry ice. CO, isheavier than air, with a vapor density of 1.53 (air=1.00).

Carbon Disulfide: A highly flammable nonpetroleumsolvent used extensively for gas chromatography because ofits relatively low signal generated in a flame ionizationdetector. Carbon disulfide has the formula CS2. Reagentgrade CS2 has an odor similar to rotten broccoli, and can beignited by contact with boiling water. It burns with a blueflame, producing CO, and SO, (sulfur dioxide). The explo-sive limits of CS2 are 1 to 50%. CS2 has a flash point of -22° F.

Carbon Monoxide: A gaseous molecule having the for-mula CO, which is the product of incomplete combustion oforganic materials. Carbon monoxide has an affinity forhemoglobin approximately 200 times stronger than oxygen’sand is highly poisonous. CO is a flammable gas which burnswith a blue flame, and has explosive limits of 12% to 75%.Carbon monoxide has approximately the same vapor densityas air, 0.97 (air=1.00).

Carbon Tetrachloride: A nonflammable liquid having theformula CC,,, formerly used as a fire extinguisher, and stillused as a solvent and cleaning agent. Carbon Tetrachlorideboils at 77° C.

Chain Reaction: A self-propagating chemical reaction inwhich activation of one molecule leads successfully toactivation of many others. Most, perhaps all, combustionreactions are of this kind.

Chemical Change: Rearrangement of the atoms, ions orradicals of one or more substances, resulting in the formationof new substances, often having entirely different proper-ties.. Also known as a chemical reaction.

Chemistry: A basic science concerned with (1) the struc-ture and behavior of atoms (elements); (2) the compositionand properties of compounds; (3) the reactions that occurbetween substances, and the resultant energy exchange and(4) the laws that unite these phenomena into a comprehen-sive system.

Chromatography: A chemical separation procedure whichseparates compounds according to their affinity for anadsorbent or absorbent material. Chromatography includesThin Layer Chromatography (TLC), Liquid Chromatogra-phy (LC), Gas Chromatography (GC) (sometimes calledGas Liquid Chromatography or GLC) and High Perfor-mance Liquid Chromatography or High Pressure LiquidChromatography (HPLC).

38

Comparison Sample: 1) A sample of material collectedfrom a fire scene which is, to the best of the investigatorsknowledge, identical in every respect to a sample suspectedof containing accelerant, but which does not contain accel-erant. 2) A sample of suspected accelerant submitted to thepurpose of comparing with any accelerant separated from adebris sample. (See Control Sample).

Combustible Liquid: A liquid which is capable of forminga flammable vapor/air mixture. All flammable liquids arecombustible. Whether a liquid is combustible or flammabledepends on its flash point and on the agency definition reliedupon. The Coast Guard classifies all liquids with a flashpoint below 80° F as flammable. The NFPA uses 100° F.

Combustion: An exothermic chain reaction between oxi-dizing and reducing agents, or between oxygen and fuel.Combustion may occur with any organic compound, or withcertain combustible elements such as hydrogen, sulfur, andfinely divided metals.

Component: 1) One of the elements or compounds presentin a system such as a phase, a mixture, a solution, or asuspension in which it may or may not be uniformly dis-persed. 2) A compound or a group of unresolved compoundsrepresented by a peak on a chromatogram.

Compound: A chemical combination of two or moreelements, or two or more different atoms arranged in thesame proportions and in the same structure throughout thesubstance. A compound is different from a mixture in thatthe components of a mixture are not chemically bondedtogether. For example, a flash may contain two volumes ofhydrogen (H2) gas and one volume of oxygen (O2) gas. Adifferent flash might contain only water vapor (H2O). In thefirst case, two gases are mixed. In the second case only onegas is present.

Concentration: The amount of substance in a stated unit ofa mixture or solution. Common methods of stating concen-tration are per cent by weight, per cent by volume, or weightper unit volume. (e.g. parts per million, billion, etc.)

Conduction: Passage of heat from one material to anotherby direct contact.

Conductivity: The ability of a material to transfer energyfrom one place to another. Thermal conductivity describesa substance’s ability to transmit heat. Electrical conductiv-ity describes a substance’s ability to transmit electricalcurrent. Conductivity is the opposite of resistivity.

Control Sample: A sample of material which is known tobe identical to a sample suspected of containing accelerantin every regard, except that the control sample does notcontain accelerant. A known blank sample. In practicalterms, control samples do not exist in the setting of a fire

scene because 1) exact conditions during the fire cannot beduplicated from location to location, and 2) exact conditionsof the substrate, i.e., carpet, etc., are not known. Carpet inRoom A may have had various items spilled on it during use.Carpet B (ten feet away) may be brand new. (See Compari-son Sample).

Convection: Transfer of heat by the movement of mol-ecules in a gas or liquid, with the less defense fluid rising.The majority of heat transfer in a fire is by convection.

Corrosion: The degradation of metals or alloys due toreaction with their environment. It is accelerated by acids,bases or heat.

Cracking: A refining process involving decomposition andmolecular recombination of organic compounds, especiallyhydrocarbons obtained by distillation of petroleum, bymeans of heat, to form molecules suitable for various usedsuch as motor fuels, solvents or plastics. Cracking takesplace in the absence of oxygen,.

-D-

Deflagration: Vigorous burning with subsonic flame propa-gation. (See Detonation)

Desorption: The process of removing an adsorbed materialfrom the solid on which it is adsorbed. (See Adsorption)

Detonation: An exothermic chemical reaction which propa-gates through reactive material at supersonic speed.

Diesel Fuel: Diesel Fuel consists mostly of hydrocarbonsranging from C10 through C24. The composition of diesel fuelmay vary with changes in latitude or changes in season. Thisvariability is provided by the refinery to control the volatilityof the product. In order to be identified as diesel fuel, asample extract must exhibit a homologous series of five ormore consecutive normal alkanes ranging from C12 throughC22. Diesel fuel has a flash point of 120 to 160° F andexplosive limits of 0.7% to 5%. Many states specify aminimum flash point for diesel fuel.

Distillation: A separation process in which a liquid isconverted to a vapor, and the vapor is then condensed backto a liquid. The usual purpose of distillation is separation ofthe compounds of a mixture. Steam distillation separates allwater insoluble liquids from solids and water soluble com-pounds in a mixture.

Drying Oil: An organic liquid which, when applied as a thinfilm, readily absorbs oxygen from the air and polymerizes toform a tough elastic film. Linseed, tung, soybean and castoroils are drying oils. ‘Under certain conditions, usuallyinvolving large surface areas and insulation, such as a pileof rags soaked with drying oils, spontaneous heating may occur.

39

-E-

Electron: A negatively charged subatomic particle whichcircles the nucleus of the atom in a cloud. Most chemicalreactions involve the making and breaking of bonds heldtogether by the sharing of electrons.

Evaporation Rate: A measure of the quantity of a liquidconverted to vapor in a unit of time. Among singlecomponent liquids, the rate varies directly with the surfacearea, the temperature and the vapor pressure, and inverselywith the latent heat of vaporization of the liquid.

Electron Capture Detector (ECD): A type of gas chro-matographic detector which is sensitive to halogenatedhydrocarbons and other molecules capable of easily gainingan electron. Electron capture is not generally used forhydrocarbon detection.

Exothermic Reaction: A chemical reaction which evolvesheat. Combustion reactions are exothermic.

Explosion: The sudden conversion of chemical energy intokinetic energy with the release of heat, light and mechanicalshock.

Element: One of 106 presently known kinds of substancesthat comprise all matter at and above the atomic level.

Elution: The process of removing adsorbed materials fromthe surface of an adsorbent such as activated charcoal. Thesolvent in this process is called the eluant.

Explosive Limit: Flammability limit. The highest orlowest concentration of a flammable gas or vapor in air thatwill explode or burn readily when ignited. This limit isusually expressed as a volume percent of gas or vapor in air.

Emission Spectroscopy: The study of the composition ofsubstances and identification of elements by observation ofthe wave lengths of radiation emitted by the substance as itreturns to a normal state after excitation by an externalsource. Generally used for elemental analysis.

Explosive Range: Flammability range. The set of allconcentrations between the upper and lower, explosivelimits of a particular gas or vapor.

Emulsion: A stable mixture of two or more immiscibleliquids in suspension.

Extraction: A chemical procedure for removing one typeof material from another. Extraction is generally carried outby immersing a solid in a liquid, or by shaking two immis-cible liquids together, resulting in the transfer of a dissolvedsubstance from one liquid to the other. Solvent extractionis one of the primary methods of sample preparation in arsondebris analysis.

Endothermic Reaction: A chemical reaction which ab-sorbs heat. -F-

Ethane: A simple alkane having the formula C2H6. A minorcomponent of natural gas. Its explosive range is 3% to12.5%. Ethane has approximately the same vapor density asair.

Fire: The light and heat manifested by the rapid oxidationof combustible materials. A flame may be manifested butis not required.

Ethanol: Ethyl alcohol. Grain alcohol. Flammable, watersoluble alcohol. Flash point of 55° F. Explosive limits of3.3% to 19%.

Ether: Diethyl ether, ethyl ether. A highly flammablesolvent which can form explosive peroxides when exposedto air. Flash point of -49F. Explosive range of 1.85% to 48%.

Fire Point: The temperature, generally a few degrees abovethe flash point, at which burning is self-sustaining afterremoval of an ignition source.

Fire Tetrahedron: Fuel, heat, oxygen and a chemical chainreaction.

Fire Triangle: Fuel, heat and oxygen.

Ethylbenzene: A component of gasoline, but also a major Flame: A rapid gas phase combustion process character-breakdown product or pyrolysis product given off when ized by a self-propagation. certain polymers are heated.

Eutectic: The lowest melting point of an alloy or solutionof two or more substances (usually metals) that is obtainableby varying the percentage of the components. Eutecticmelting sometimes occurs when molten aluminum or mol-ten zinc comes in contact with solid steel or copper.

Evaporation: Conversion of a liquid to the vapor state. Set

Flame Ionization Detector (FID): A nearly universal gaschromatographic detector., It responds to almost all organiccompounds. An FID does not respond to nitrogen, hydro-gen, helium, oxygen, carbon monoxide or water. Thisdetector ionizes compounds as they reach the end of thechromatographic column by burning them in an air/hydro-gen flame. As the compounds pass through the flame, theconductivity of the flame changes, generating a signal. This

also Vaporization.

40

is the most commonly used detector in arson debris analysis.

Flame Propagation: Travel of a flame through a combus-tible gas/air or vapor/air mixture.

Flammability Limit: (See Explosive Limit)

Flammability Range: (See Explosive Range)

Flammable Liquid: A combustible liquid that has a flashpoint below 80°F according to the Coast Guard, 100°Faccording to NFPA. Liquids having a vapor pressure over40 pounds per square inch at 100°F are classified as flam-mable gases. Flammable liquids are a special group ofcombustible liquids.

Flammable Vapor: A vapor/air mixture of any concentra-tion within the flammability range of that vapor.

Flash Fire: A fire that spreads with unusual speed, as onethat races over flammable liquids or through combustiblegases. The temperature at which a pool of liquid willgenerate sufficient vapors to form an ignitable vapor/airmixture. The temperature at which a liquid will produce itslower explosive limit in air. Flash point describes one ofseveral very specific laboratory tests. Frequently, materialscan be made to burn below their flash point if increasedsurface area or mechanical activity raises the concentrationof vapor in air above the lower explosive limit.

Fractionation: The separation of one group of compoundsin a mixture from another, generally by distillation.

Fuel Oil: A heavy petroleum distillate ranging from #1(kerosene or range oil), #2 (diesel fuel), up through #6(heavy bunker fuels). To be identified as fuel oil, a samplemust exhibit a homologous series of normal alkanes rangingfrom C9 upward.

-G-

Gas Chromatography (also known as Gas Liquid Chro-matography):. The separation of organic liquids or gasesinto discrete components or compounds seen as peaks on achromatogram. Separation is done in a column which isenclosed in an oven held at a specific temperature, orprogrammed to change temperature at a reproducible rate.The column separates the compounds according to. theiraffinity for the material inside the column (stationary phase).Columns can be either packed or capillary. Packed columnsemploy a powder) substance which may be coated with anonvolatile liquid phase. A capillary column is a glass orquartz tube coated with a nonvolatile liquid. Gas Chroma-tography (GC) is the accepted method for identification ofhydrocarbon mixtures normally used as accelerants, andmust be performed in order to have a valid identification ofpetroleum distillates.

Gasoline: A mixture of more than 200 volatile hydrocar-bons in the range of C4 to C12, suitable for use in a sparkignited internal combustion engine. Regular automotivegasoline has a flash point of -40°F.

-H-

Headspace Concentration: A technique for concentratingall or most of the flammable or combustible liquid vapors ina sample on to a tube of charcoal, a wire coated with charcoal,a charcoal coated polymer, or some other adsorbing materialwhich will later be desorbed in order to analyze the concen-trated vapors. This is a primary form of sample preparationin arson debris analysis. This is also known as adsorption/elution, vapor concentration, or total headspace.

Heat: A mode of energy associated with and proportionalto molecular motion that may be transferred from one bodyto another by conduction, convection or radiation.

Heptane: An alkane having the formula C7H16, flash pointof 25°F and explosive limits of 1.2% to 6.7%.

Hexane: An alkane having the formula C6H14. Flash pointof -9°F. Explosive limits of 1.2% to 7.5%.

Homologous Series: A series of similar organic com-pounds, differing only in that the next higher member of theseries has an additional CH2 group (one carbon atom and twohydrogen atoms) in its molecular structure. Fuel oils arecharacterized by the presence of an identifiable homologousseries of normal alkanes.

Hydrocarbon: An organic compound containing onlycarbon and hydrogen.

Hydrogen: The simplest element. Atomic Number 1.Hydrogen gas has a specific gravity of 0.0694 (air = l), soit is much lighter than air. Hydrogen is highly flammable,forming water upon combustion. Explosive limits are 4% to75%.

-I-

Ignition: The means by which burning is started.

Ignition Temperature: The minimum temperature towhich a fuel must be heated in order to initiate or cause self-sustained combustion independent of another heat source.

Immiscible: Describes substances of the same phase or stateof matter (usually liquids) that cannot be uniformly mixedor blended.

Incendiaries: Substances or mixtures of substances consist-ing of a fuel and an oxidizer used to initiate a fire.

41

Incendiary Fire: Fire set by human hands.

Incidental Accelerants: Flammable or combustible liquidswhich are usual and incidental to an area where they aredetected. Gasoline is incidental to an area where gasolinepowered appliances are kept. Kerosene is incidental to anarea where a kerosene heater is kept. Flammable liquidsmay also comprise a part of a product such as insecticide,furniture polish, or paint. Additionally, certain asphalt-containing building materials may yield detectable quanti-ties of fuel oil components.

Infrared Spectrophotometry (IR): An analytical tech-nique which utilizes an instrument which passes infraredradiation through a sample or which bounces infrared radia-tion off the surface of a sample. A very sensitive heatdetecting device measures the amount of infrared radiationabsorbed as the wavelength of the radiation reaching thedetector is changed. IR can give useful information aboutthe type of compounds present in a sample, but it is notcapable of precisely identifying a complex mixture. Infra-red is very useful in identifying single solvent acelerants.

Intumescent Char: In plastics, the swelling and charringwhich results in a higher ignition point. Used in thepreparation of flame retardant materials.

Ion: An atom, molecule or radical that has lost or gained oneor more electrons, thus acquiring the electric charge. Posi-tively charged ions are cations; negatively charged ions areanions.

Isomer: One or two or more forms of a chemical compoundwhich have the same number and type of each atom, but adifferent arrangement of atoms.

Isoparaffins: A mixture of branched alkanes usually avail-able as a narrow “cut” of a distillation. Exxon manufacturesa group of products known as “isopars” ranging from IsoparA through Isopar J. These solvent mixtures have a varietyof uses. Gulf Oil manufactures a similar series of solvents,the most commonly available of which is Gulf Lite CharcoalStarter Fluid which is roughly equivalent to Exxon’s Isopar G.

Isothermal: A type of gas chromatographic analysis where inthe column is maintained at a uniform temperature through-out the analysis. (See Programming).

- K -

Kerosene (#1 Fuel Oil): Flash point generally between 100and 150 degrees F. Explosive limits of 0.7% to 5.0%.Kerosene consists mostly of C9 through C17 hydrocarbons. Inorder to be identified as kerosene, a sample extract mustexhibit a homologous series five consecutive normal al-kanes between C9 and C17. Kerosene is the most common“identical: accelerant, as it is used in numerous household

products ranging from charcoal lighter fluid to lamp oil topaint thinner to insecticide carriers. It is also used as jet fuel.K-l kerosene has a low sulfur content required for use inportable space heaters.

Ketone: A type of organic compound having a carbonylfunctional group (C=O) attached to two alki groups. Ac-etone is the simplest example of a ketone.

-M-

Magnesium: A silvery metal used in some metal incendi-aries. The dust is highly explosive. Ignition point of 650°F.

Mass Spectrometry: A method of chemical analysis whichvaporizes, then ionizes the substance to be analyzed, andthen accelerates the ions through a magnetic field to separatethe ions by molecular weight. Mass spectrometry can resultin the exact identification of an unknown compound, and isa very powerful analytical technique, especially when com-bined with chromatography.

Meta-ethyltoluene (m-ethyltoluene): A component ofgasoline.

Matrix: Substrate. The material from which a substance ofinterest is removed for analysis.

Methane: The simplest hydrocarbon and the first memberof the paraffin (alkane) series; having a formula CH4.Methane is the major constituent of natural gas. Methane hasa heating value of 1009 BTU/cubic foot. Its explosive limitsare 5% to 15%.

Methanol: Methyl alcohol. Wood alcohol. The simplestalcohol. Methanol is water soluble and has a flash point of54°F and explosive limits of 6% to 36.5%.

Methyl Silicone: A nonvolatile oily liquid used in gaschromatography to separate nonpolar compounds. Methylsilicone columns typically separate compoundsaccording totheir boiling point.

Methylstyrene: A common polymer pyrolysis product.

Mineral Spirits:’ A medium petroleum distillate rangingfrom C8 to C12. The flash point of mineral spirits, sometimesknown as mineral turps, is commonly used as a solvent ininsecticides and certain other household products. Manycharcoal lighter fluids are composed almost entirely, ofmineral spirits.

Molecular Weight: The sum of the atomic weights of allof the atoms within a molecule. Generally, molecules of thesame type have higher boiling points if the molecular weightis higher.

42

Molecule: The smallest particle into which a substance canbe divided without changing its chemical properties. Amolecule of an element consists of one atom, or two or moreatoms that are alike. A molecule of a compound consists oftwo or more different atoms.

Monomer: The simplest unit of a polymer. Ethylene is thesmallest unit of polyethylene. Styrene is the smallest unit ofpolystyrene.

-N-

Naphtha: An ambiguous term which may mean high flashnaphtha (mineral spirits), or low flash naphtha (petroleumether, low boiling ligroin) or something altogether different.Flash point and explosive limits vary. The term naphtha isso ambiguous that it should not be used.

Natural Gas: A mixture of low-molecular weight hydrocar-bons obtained in petroleum bearing regions throughout theworld. Natural gas consists of approximately 85% methane,10% ethane and the balance propanes, butanes and nitrogen.Since it is nearly odorless, an odorizing agent is added tomost natural gas prior to final sale.

Nebulize: To form a mist of fine droplets from a liquid. Toatomize.

Nitrogen: A gaseous element which makes up approxi-mately 80% of earth’s atmosphere. Nitrogen is relativelyinert and does not support either combustion or life. Nitro-gen is usually found in the molecular N2 form.

-O-

Octane: 1) An alkane having the formula C8H18. Flash pointof 56°F. Explosive limits of 1% to 3.2%. 2) A measure ofthe resistance of a sample of gasoline to premature ignition(knocking). 100 octane fuel has the knocking resistance of100% iso-octane (w,2,4-trimethyl pentane). Zero octanefuel has the knocking resistance of n-heptane. 89 octane fuelhas the knocking resistance of a mixture of 89% iso-octaneand 11% n-heptane.

Olefin: An alkene. An organic compound similar to analkane, but containing at least one double bond. Olefinshaving the formula CnH2n. The simplest olefin is ethylene,

C2H4 .

Organic Chemistry: The study of the carbon atom and thecompounds it forms, mainly with the 20 lightest elements,especially hydrogen, oxygen and nitrogen. Some 3 millionorganic compounds have been identified and named.

Oxidation: Originally, oxidation meant a chemical reac-tion in which oxygen combines with another substance. Theusage of the word has been broadened to include any reactionin which electrons are transferred. The substance whichgains electrons is the oxidizing agent.

Oxygen: A gaseous element which makes up approxi-mately 20% of the earth’s atmosphere. It is usually found inthe molecular O2 form. Oxygen is the most abundantelement on earth.

-P-

Pentane: An alkane having the formula C5H12, flash pointof -40°F, and explosive limits of 1.4% to 8%. Pentane isfrequently used to extract flammable or combustible liquidresidues from debris samples.

Petroleum Distillates: By-products of the refining of crudeoil. Low boiling or light petroleum distillates (LPD) arehighly volatile mixtures of hydrocarbons. These mixturesare sometimes called ligroin, petroleum, ether, or naphtha.LPDs are used as cigarette lighter fluid, as copier fluid, andas solvents. Medium boiling petroleum distillates (MPD)are sometimes known as mineral spirits, and are used ascharcoal starters, as paint thinners, as solvents for insecti-cides and other products, and as lamp oils. High Boiling orHeavy petroleum distillates (HPD) are combustible liquidssuch as kerosene and diesel fuel.

pH: A number used to represent the acidity or alkalinity ofan aqueous solution. pH7 is neutral. Acids have a pH below7, the lower the pH, the more acidic the solution. Bases havea pH above 7. The higher the pH, the more basic or alkalinethe solution.

Photoionization Detector (PID): A type of detector usedin chromatography which employs ultraviolet radiationrather than a flame to ionize compounds as they pass through.a detector. Photoionization detectors are particularly sensi-tive to aromatic compounds.

Polarity: The measure of an electrical charge on a mol-ecule. Most flammable or combustible liquids are nonpolar.Many water soluble compounds,. including alcohols andacetone, are polar.

Polymer: A large molecule consisting of repeating units ofa monomer. Polymers may be natural, such as cellulose, orsynthetic, such as most plastics.

Programming: A method of gas chromatographic analysiswhich reproducibly raises the temperature of the column soas to allow better resolution of the components over a widerange of boiling points.

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Propane: An alkane having the formula C3H8. Propane isthe major constituent of LP gas. Explosive limits of 2.4% to9%. One cubic foot of propane has a heating value of 2500BTU’s.

Pseudocumene: (1,2,4-trimethyl benzene) A component ofgasoline.

Pyrolysis: The transformation of a substance into one ormore other substances by heat alone without oxidation.

Pyrophoric Distillation: The slow drying and passivepyrolysis of wood materials.

-R-

Radiation: 1) Transfer of heat through electromagneticwaves from hot to cold. 2) Electromagnetic waves of energyhaving frequency and wavelength. The shorter wavelengths(higher frequencies) are more energetic. The electromag-netic spectrum is comprised of a) cosmic rays, b) gammarays, c) x-rays, d) ultraviolet rays, e) visible light rays,f) infrared, g) microwaves and h) radio waves.

Resolution: 1) In chromatography, a measure of the sepa-ration of components. 2) In spectroscopy, a measure of theability of the instrument to detect individual absorbancepeaks.

Retention Time: The length of time required for a com-pound or component of a mixture to pass through a chro-matographic column.

-S-

Saturation: The state in which all available bonds of anatom are attached to other atoms. Alkanes are saturated.Olefins are unsaturated.

Spalling: Destruction of a surface by frost, heat, corrosion,or mechanical causes. Concrete exposed to intense heat mayspall explosively. Expansion and contraction of the concreteas well as vaporizing moisture contained in the concretecontribute to this effect. It does not necessarily mean anaccelerant was used.

Spectrophotometer: An analytical technique devoted tothe identification of the elements and the elucidation ofatomic and molecular structure by measurement of theradiant energy absorbed or emitted by a substance in any ofthe wavelengths of the electromagnetic spectrum in re-sponse to excitation by an external energy source.

Spontaneous Heating: Also known as Spontaneous Com-bustion. Initially, a slow, exothermic reaction at ambienttemperatures. Liberated heat, if undissipated (insulated),accumulates at an increasing rate and may lead to spontane-ous ignition of any combustibles present. Spontaneousignition occurs sometimes in haystacks, coal piles, warmmoist cotton waste, and in stacks of-rags coated with dryingoils such as cottonseed or linseed oil.

Styrene: Vinylbenzene. An aromatic compound having theformula C6H5C2H3. The monomer of polystyrene plastic. Acommon product of polymer pyrolysis.

Substrate: Matrix. The material from which a substance tobe analyzed is removed.

Sulfur: A nonmetallic yellow element. A constituent ofblack powder, sulfur burns readily when in powdered form.

Terpenes: Volatile hydrocarbons which are normal con-stituents of wood.

Thermal Conductivity Detector: A type of gas chromato-graphic detector which is sensitive to the change in theability of the gases emerging from the column to conductheat. A thermal conductivity (TC) detector is not assensitive as a flame ionization detector,’ but is capable ofdetecting some molecules; such as water, which give nosignal in FID.

Thin Layer Chromatography (TLC): A procedure forseparating compounds by spotting them on a glass platecoated with a thin (about 0.01 inch) layer of silica oralumina, and “developing” the plate by allowing a solventto move upward by capillary action. TLC is especiallyuseful for identifying and comparing materials which arehighly colored or which fluoresce under ultraviolet light.TLC is used extensively in explosive analysis and in thecomparison of gasoline dyes.

Toluene: Methylbenzene. An aromatic compound havingthe formula C6H5CH3. A major component of gasoline.Toluene has a flash point of 40°F and explosive limits of1.2% to 7%.

Turpentine: 1) Gum. The pitch obtained from living pinetrees. A sticky viscous liquid. 2) Oil. A volatile liquidobtained by steam distillation of gum turpentine, consistingmainly of pinene and diterpene. Turpentine is frequentlyidentified in debris samples containing burned wood.

44

- V -

Vaporization: The physical change of going from a solidor a liquid into a gaseous state.

Volatile: Prone to rapid evaporation. Both combustible andnoncombustible materials may be volatile.

-X-

X-ray Diffraction: An analytical technique used to identifycrystalline solids by measuring the characteristic spacesbetween layers of atoms or molecules in a crystal. X-raydiffraction can be very useful in the identification of explo-sive residues.

X-ray Fluorescence: A spectrophotometric analytical tech-nique which uses x-rays to excite the samples. X-rayfluorescence will allow the characterization of the elementalcontent of a sample.

Xylene: Dimethylbenzene. An aromatic compound having theformula C6H4(CH3)2. Xylene is a major component of gasoline.A mixture of toluene and xylene is frequently used as automotivepaint thinner. Xylene is actually a mixture of three isomers, ortho,meta and para xylene, which have the methyl groups in differentpositions relative to each other on the benzene ring. The flashpoints of these isomers range from 81° to 115°F. Paraxylene, witha flash point of 81°F, is used to calibrate flash point testers. Theexplosive limits of xylene are 1.0% to 7.0%.

45