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  • Forensic Science: An Introduction

  • Forensic ScienceIn its broadest definition it is the application of science to lawApplies to the knowledge and technology of science for the definition and enforcement of such lawsDefinition: the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system

  • Sciences involvedChemistryBiologyPhysicsGeologyForensic pathologyForensic psychologyForensic Odontology

  • History of Forensic ScienceSir Arthur Conan Doyle: fictional character Sherlock Holmes had a great influence on popularizing the study of crime scenesHolmes was the first to apply the principles of serology (blood typing and analysis), fingerprinting, firearm identification and document examinationFirst book in 1887 A Study in Scarlet

  • Important PeopleMathieu Orfila (1787-1853) father of forensic toxicology; detection of poisons and their effects

    Alphonse Bertillon (1853-1914) scientific system for personal identification; taking body measurements as a means of distinguishing people; father of criminal identification

  • Important PeopleFrancis Galton (1822-1911) study of fingerprints and developed method for classifying them for filing

    Karl Landsteiner in 1901 discovered ABO blood types

    Leone Lattes (1887-1954) devised a procedure for determining blood group of a dried bloodstain

  • Important PeopleCalvin Goddard (1891-1955) comparison microscope to identify bullets

    Albert Osborn (1858-1946) document examination

    Walter McCrone (1916-2002) known as the worlds preeminent microscopist; instructor, and author

  • Important PeopleHans Gross (1847-1915) Austrian judge who described the application of scientific disciplines to the field of criminal investigation.Zoology, botany, anthropology, fingerprinting

    Edmond Locard (1877-1966) founder and director of the Institute of Criminalistics at the University of Lyons; workable crime lab

  • Important PeopleEdmond Locard: Locards Exchange Theory: the exchange of materials between two objects that occurs whenever two objects come into contact with one antherLocard believed every criminal can be connected to a crime by dust particles carried from the crime scene

  • Major influencers#1 reason for increased need of trained scientists is the increase in drug sale and usage in the worldAll illicit drug seizures must be sent to a forensic lab for confirmatory chemical analysis before the case can go to court

  • 4 Federal Crime LabsFBI: largest crime labDEA Drug Enforcement Agency: analysis of drugs seized in violation of federal laws for production, sale and transportation of drugsATFE Bureau of Alcohol Tobacco Firearms and Explosives: responsible for analyzing alcoholic beverages and documents relating to tax law enforcement and for examining weapons, explosive devices, and related evidenceU.S. Postal Inspection Services: maintains lab concerned w/criminal investigations relating to the postal service

  • Crime Lab ServicesBasic ServicesPhotography Physical Science Biology/DNAFirearmsDocument Examination

    Optional ServicesToxicologyLatent FingerprintPolygraphyVoice AnalysisForensic PsychiatryForensic OdontologyForensic EngineeringForensic Computer and Digital Analysis

  • What Forensic Scientists DoAnalyze physical evidenceUse scientific methodsDetermine admissibility of evidenceFrye v US (1923) general acceptanceJudge scientific evidenceDaubert case (1993) trial judge is gatekeeperProvide expert testimonyFurnish training

  • Physical EvidenceAnything physical objects that can link a crime to its victims or to suspects.Has to be collected from crime sceneMust be relevant to the crime Requires the collector to understand what the capabilities and limitations of the crime lab are

  • Physical EvidenceCrime labs do not solve crimes, only add evidence to help police investigation link the suspect to the crime.The forensic scientists must know how to collect and preserve evidence found at the crime scene

  • Arriving at the Crime SceneSecure and isolate the crime sceneDetermine boundaries of crime scene and priorities for evidence collectionRough sketch Finished sketchPhotograph Videotaping Notes

  • Collecting EvidenceConduct a systematic search for evidence; be unabiased and thorough.Field techniciansWhat to look for depends on the crime and what specific locations of the crime scene would most likely be affectedMicroscopic or massive objectsCollect carriers of possible evidenceVacuum or sweeping collected

  • Packaging of EvidencePrevent any changes from occurring (contamination, breakage, evaporation, bending, loss)Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possiblePackage evidence separately

  • Tools for Collecting EvidenceForcepsEvidence envelopes and pill bottlesSwabsSpecial concerns (mold, evaporation)Various light sourcesLatent fingerprintsMobile crime labs or better yet crime scene search vehicle

  • Chain of custody

    Continuity of possession; every person who touched it must be accounted forStandards for collecting, labeling, and submitting evidence forms are necessary for court Labels include collectors initials, location of evidence, date of collection. Identification numbers must also be used

  • Submission of EvidenceStandard/reference samplesSubstance controlsEvidence submission form will detail the evidence collect and particular type of examination/analysis requested. Lab tech not bound by requests

  • Common Types of EvidenceCommon Types of EvidenceBlood, semen, and salivaDocumentsDrugsFibersFingerprintsFirearms and ammunitionGlassHairImpressionsOrgans and physiological fluidsPaintPetroleum productsPlastic bagsPlastic, rubber, and other polymersPowder residuesSerial numbersSoil and mineralsTool marksVehicle lightsWood and other vegetative matter

  • Examination of Physical EvidenceIdentificationDetermining the identity of a substance with a near absolute certainty while ruling out other substancesComparisonComparing the evidence to one or more selected references and drawing a conclusion about its origins.Individual characteristics properties of evidence that can be attributed to a common source with extremely high certainty. (eg. fingerprints, DNA, bullets)Class characteristics properties of evidence that can be associated with a group and never with a single source. ( eg. Blood type, tire marks)

  • Significance of Physical EvidenceAssessing the values of evidenceClass characteristics of evidence is valuable in corroborating events.Multiple class evidence can lead to a high level of certainty of originCautions and limitations of evidence A person can be exonerated or excluded from suspicion if evidence collected from the crime scene is different from the reference samples collected from the person.

  • Forensic DatabasesOne-on-one comparison requires a suspectComputerized databases help link evidence to peopleFingerprint databases IAFISDNA database CoDISBallistics database IBISAutomative Paint database PDQShoeprint database - SICaR

  • Crime-Scene Reconstruction

    The method used to support a likely sequence of events at a crime scene by observing and evaluating physical evidence and statements made by those involved with the incidentCombined efforts of MEs, CSI, and law enforcement personnelExamples: was body moved, bullet trajectory, blood splatter