Forensic Sciences: Another Introduction

Science and Science and LawLaw

Forensic Science - Forensic Science - in its broadest in its broadest definition is the definition is the application of application of science to lawscience to law

As our society As our society grows more grows more complex, it has complex, it has become more become more dependent on laws dependent on laws to regulate the to regulate the activities of its activities of its members.members.

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Forensic ScienceForensic Science 1-Offers the knowledge and technology of

science for the definition and enforcement of laws.

2-It cannot offer final and authoritative solutions, however, Forensic Science does play an important and unique roll in the criminal justice system.

3-It uses the scientist's ability to supply accurate and objective information that reflects the events of a crime

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The major areas The major areas reviewedreviewed

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Forensic Forensic MedicineMedicine

The application of The application of medicine and medical medicine and medical science to legal problems. science to legal problems.

Practitioners of forensic Practitioners of forensic medicine are doctors of medicine are doctors of medicine with special medicine with special certification in pathology certification in pathology & forensic pathology. & forensic pathology.

Most of them are Medical Most of them are Medical Examiners. Examiners.

They are concerned with They are concerned with determining cause and determining cause and circumstances in cases of circumstances in cases of questioned death. questioned death.

They also can be involved They also can be involved in matters of insurance in matters of insurance claims, & sometimes claims, & sometimes cases of malpracticecases of malpractice

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Forensic Forensic OdontologyOdontology

Commonly called Forensic Commonly called Forensic DentistryDentistry

The application of The application of dentistry to human dentistry to human identification problems. identification problems.

Forensic odontolgists are Forensic odontolgists are dentists who specialize in dentists who specialize in the forensic aspect of their the forensic aspect of their field. field.

They are concerned with They are concerned with the identification of the identification of persons based upon their persons based upon their dentition, usually in cases dentition, usually in cases of otherwise of otherwise unrecognizable bodies or unrecognizable bodies or in mass disasters. in mass disasters.

They also analyze and They also analyze and compare bite mark compare bite mark evidence.evidence.

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Forensic Forensic AnthropoloAnthropolo

gygy

Personal identification Personal identification based on bodily remains based on bodily remains (particularly skeletal) (particularly skeletal)

Practitioners are Practitioners are anthropologists who are anthropologists who are interested in Forensic interested in Forensic Science. Science.

Other areas of forensic Other areas of forensic anthropology include anthropology include Maintaining data bases Maintaining data bases

on bodily structures as on bodily structures as functions of race, sex, functions of race, sex, age, stature, and so age, stature, and so forth. forth.

Facial reconstructionFacial reconstruction Interpretation of Interpretation of

footprint or shoe-print footprint or shoe-print evidenceevidence

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Forensic Forensic ToxicologyToxicology

The determination The determination of toxic substances of toxic substances in human tissues in human tissues and organs. and organs.

Much of the work Much of the work concerns the role concerns the role toxic agents may toxic agents may have played in have played in causing or causing or contributing to the contributing to the death of a person.death of a person.

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Trace Trace Evidence Evidence AnalysisAnalysis

Includes all areas of Includes all areas of trace and transfer trace and transfer evidence:evidence: soil and glasssoil and glass hair and fibershair and fibers blood blood physiological fluidsphysiological fluids arson accelerant and arson accelerant and

explosive residuesexplosive residues drug identificationdrug identification patterns and imprintspatterns and imprints

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Questioned Questioned Documents Documents

ExaminationExamination

The comparison and The comparison and interpretation of ...interpretation of ... handwritinghandwriting mechanically mechanically

produced material produced material (typing, printing)(typing, printing)

photocopied photocopied materialmaterial

The analysis of paper, The analysis of paper, inks, and other inks, and other materials used to materials used to produce documentsproduce documents

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Firearm & Firearm & Toolmark Toolmark

ExaminationExamination

Firearm identification Firearm identification Comparison of Comparison of

markings on bullets, markings on bullets, cartridge cases, and cartridge cases, and shell cases.shell cases.

Determining if a bullet Determining if a bullet has been fired from a has been fired from a particular weapon. particular weapon.

Toolmark Toolmark examinations are examinations are concerned with the concerned with the association of a association of a particular impression particular impression with a particular tool.with a particular tool.

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Fingerprint Fingerprint ExaminationsExaminations

Classification of Classification of fingerprints fingerprints

Maintaining Maintaining fingerprint databases fingerprint databases

Development and Development and lifting of latent prints lifting of latent prints

Comparisons of Comparisons of known and unknown known and unknown fingerprints to fingerprints to determine a matchdetermine a match

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The work of a The work of a Forensic ScientistForensic Scientist

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Recognition of physical Recognition of physical evidenceevidence

Identification of physical Identification of physical evidenceevidence

Individualization of Individualization of physical evidencephysical evidence

Evaluation of physical Evaluation of physical evidenceevidence

Reconstruction of the Reconstruction of the crimecrime

The Goals of a Forensic Scientist

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RECOGNITIONRECOGNITION

Almost anything can be physical Almost anything can be physical evidence and it is very dependant on evidence and it is very dependant on the type of crime committedthe type of crime committed

With practice and experience With practice and experience evidence recognition becomes easierevidence recognition becomes easier

Beware…submitting too much Beware…submitting too much evidence is just as bad as submitting evidence is just as bad as submitting too littletoo little

Although it may Although it may seem obvious it is seem obvious it is important to be able important to be able to recognize what is to recognize what is and is not physical and is not physical evidenceevidence

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IdentificationIdentification Identification of physical evidence may be Identification of physical evidence may be

regarded as a classification schemeregarded as a classification scheme Evidence is assigned into categories with like Evidence is assigned into categories with like

items. items. Initial categories are broad and then narrowed Initial categories are broad and then narrowed

down as more information is obtaineddown as more information is obtained ExampleExample

Blue substanceBlue substance Blue paintBlue paint Blue car paintBlue car paint Blue car paint from Ford Manufacturing Blue car paint from Ford Manufacturing

CompanyCompany Blue car paint from Ford produced 1998-Blue car paint from Ford produced 1998-

20002000 Blue car paint from Ford produced 1998-Blue car paint from Ford produced 1998-

2000, used on Mustang and Explorer2000, used on Mustang and Explorer 16

Class EvidenceClass Evidence To identify an object in Forensic To identify an object in Forensic

Science is really to separate it by classScience is really to separate it by class Class characteristics are the properties Class characteristics are the properties

that all the members of a certain group that all the members of a certain group of objects or substances have in of objects or substances have in common.common.

The previous “paint” example was a The previous “paint” example was a refined class evidence identificationrefined class evidence identification

The “paint” was identified by comparing The “paint” was identified by comparing its class characteristics with those of its class characteristics with those of known standards or previously known standards or previously established criteria. established criteria.

The “paint” is considered CLASS The “paint” is considered CLASS EVIDENCEEVIDENCE

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Class Evidence ExamplesClass Evidence Examples

Single layered paint Single layered paint SoilSoil Glass fragments too small to fit Glass fragments too small to fit

back togetherback together HairsHairs FibersFibers

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The Value of Class The Value of Class EvidenceEvidence

Many lawyers try to discredit class Many lawyers try to discredit class evidence because it cannot be limited to evidence because it cannot be limited to just one possible source just one possible source

However Class Evidence DOES HAVE However Class Evidence DOES HAVE VALUE. VALUE.

Look around room, most have different Look around room, most have different clothes on. If I were to pick a fiber from clothes on. If I were to pick a fiber from one persons clothes in this room, that fiber one persons clothes in this room, that fiber could possibly pick out the single source or could possibly pick out the single source or at least narrow the fieldat least narrow the field

Some class evidence holds little forensic Some class evidence holds little forensic value such as fiber from jeans or white value such as fiber from jeans or white cotton shirts…they are too commoncotton shirts…they are too common

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IndividualizationIndividualization Individualization is Individualization is uniqueunique to to

Forensic ScienceForensic Science It refers to the demonstration that a It refers to the demonstration that a

particular sample is unique, even particular sample is unique, even among members of the same class. among members of the same class.

It may also refer to the It may also refer to the demonstration that a questioned demonstration that a questioned piece of physical evidence and a piece of physical evidence and a similar known sample have a similar known sample have a common origin.common origin.

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More Than CLASSMore Than CLASS In addition to class characteristics, In addition to class characteristics,

objects and materials possess individual objects and materials possess individual characteristics that can be used to characteristics that can be used to distinguish members of the same class. distinguish members of the same class.

The nature of these individual The nature of these individual characteristics varies from one type to characteristics varies from one type to another, but forensic scientists try to another, but forensic scientists try to take advantage of them in effort to take advantage of them in effort to individualize a piece of physical individualize a piece of physical evidence by some type of comparison evidence by some type of comparison process. process.

Only a few types of physical evidence Only a few types of physical evidence (primarily physical pattern evidence) (primarily physical pattern evidence) can be truly individualizedcan be truly individualized

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Evidence that Contains Evidence that Contains Individualizing Individualizing CharacteristicsCharacteristics

FingerprintsFingerprints HandwritingHandwriting BulletsBullets ToolmarksToolmarks ShoeprintsShoeprints Tire printsTire prints Glass fragments that can be Glass fragments that can be

matchedmatched

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Problems with WordsProblems with Words Identification is sometimes used to Identification is sometimes used to

mean personal identificationmean personal identification Fingerprints for example, can be used Fingerprints for example, can be used

to “identify” an individualto “identify” an individual The terminology is unfortunate, since The terminology is unfortunate, since

this process is really this process is really “individualization” “individualization”

Likewise, dental evidence and dental Likewise, dental evidence and dental records are used in “identifying” dead records are used in “identifying” dead bodies...when they are really bodies...when they are really individualizingindividualizing

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The GOAL...The GOAL... Ultimate goal would be to move all Ultimate goal would be to move all

class evidence to individualistic, not class evidence to individualistic, not very likelyvery likely

Hair is trying to make the Hair is trying to make the move...something like paint probably move...something like paint probably never will.never will.

For human evidence to be For human evidence to be individualistic, the odds of two people individualistic, the odds of two people matching the same piece of evidence matching the same piece of evidence must be 1 in about 7.5 billion, which is must be 1 in about 7.5 billion, which is the population of the earth.the population of the earth.

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Is DNA Individualistic??Is DNA Individualistic?? Up to the late 1990’s, the smallest odds Up to the late 1990’s, the smallest odds

were 1 in 100 million. This narrowed it to were 1 in 100 million. This narrowed it to 1 in 50 people on the earth, but it still 1 in 50 people on the earth, but it still was not individualistic.was not individualistic.

More recently with new DNA techniques, More recently with new DNA techniques, the new odds are proving to be the new odds are proving to be “individualistic” “individualistic”

However we still have the problem of However we still have the problem of identical twins having the same DNA identical twins having the same DNA (but they do have different fingerprints!)(but they do have different fingerprints!)

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ReconstructiReconstructionon

Reconstruction refers to theReconstruction refers to theprocess of putting the “pieces” process of putting the “pieces” of a case or situation togetherof a case or situation together The objective is to reach an The objective is to reach an

understanding of a sequence of understanding of a sequence of past events based on the record of past events based on the record of physical evidence physical evidence

Identification and Identification and individualization of physical individualization of physical evidence plays a crucial role in evidence plays a crucial role in providing data for reconstructionsproviding data for reconstructions

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