Xã hội học - The crime laboratory

SEVENThe Crime LaboratoryLEARNING OBJECTIVESDefine and distinguish forensic science and criminalistics Understand the importance of an investigator's understanding of crime laboratory capabilities Describe the three measures of effectiveness of crime laboratories Distinguish the Frye test from the Daubert test regarding the admissibility of scientific evidence Explain the role and importance of DNA analysis in criminal investigation Identify the latest technologies in DNA evidence investigation and data banking Highlight the process of fingerprint identification and comparison Describe AFIS and IAFIS Describe NIBIN Briefly explain the techniques and methods used by both the ATF and FBI crime laboratories to examine evidence7-1FORENSIC SCIENCEForensic science is that part of science applied to answering legal questions. It includes:The examinationThe evaluationAnd the explanation of physical evidence in law7-2CRIMINALISTICSCriminalistics deals with the study of physical evidence related to a crimeFrom such a study a crime may be reconstructedCriminalistics is interdisciplinary in nature drawing upon: MathematicsPhysicsChemistryBiology7-3UNDERSTANDING CRIME LAB CAPABILITIESIt is not unusual to find situations in which investigators not acquainted with the services of the crime laboratory expect too much from scientific analysisThe analysis of evidence can be no better than the samples submittedThe investigator therefore has a vital role to play in the success of laboratory examinations7-4MEASURES OF EFFECTIVENESS OF CRIME LABORATORIESThe effectiveness of crime laboratories and the services performed are measured by:QualityProximityTimeliness7-5CRIME LAB PERSONNELHave degrees in physical sciencesAre well trainedMay testify as experts in courts7-6(Courtesy New Jersey State Police)LOCATION OF CRIME LABORATORIES IN FLORIDAThe proximity of crime labs to the police is importantIn Florida's model labs are located throughout the stateThis maximizes crime lab use by the police7-7FRYE V. UNITES STATES AND DAUBERT V MERRELL DOW PHARMACEUTICALS, INC.Frye v. United States - the 1923 federal court decision ruling that for a scientific technique to be admissible in evidence, it must be sufficiently established to have gained general acceptance in its particular fieldDaubert v. Merrell Dow Pharmaceuticals Inc. The 1993 U.S. Supreme Court decision holding that the Frye test was no longer valid in federal courts; a trial court must determine whether the testimony of an expert is based on a scientifically valid methodology and can properly be applied to the facts of the caseThe application of Daubert presents a challenge to crime labs to ensure their lab results will be admissible7-8“SNIFFING” ROBOTRobots are used at crime scenes to:Detect explosivesLocate drugsCollect physical evidence7-9(Courtesy Nashville Police Department)DNA ANALYSISAdvances in technology have helped DNA testing to become an established part of criminal justice procedureQuestions about the validity and reliability of forensic DNA test methods have been addressed, and for the most part validity and reliability are establishedAs a result of DNA testing, traditional blood testing and saliva testing have been rendered obsolete DNA is found in these substances and, if fact, is found in all body tissues and fluidsDNA evidence may be found and collected from virtually everywhere at a crime scene7-10SOURCES OF DNA EVIDENCEThese are common sources of blood and DNA evidence that investigators need to be aware of in conducting crime scene searches. 7-11EvidencePossible Location of DNA on the EvidenceSource of DNABaseball bat or similar weaponHat, bandana, or maskEyeglassesFacial tissue or cotton swabDirty laundryToothpickUsed cigaretteStamp or envelopeTape or ligatureBottle, can, or glassUsed condomBlanket, pillow, or sheet“Through and through” bulletBite markFingernail or partial fingernailHandle, endInsideNose or ear pieces, lensSurface areaSurface areaTipsCigarette buttLicked areaInside or outside surfaceSides, mouthpieceInside or outside surfaceSurface areaOutside surfacePerson’s skin or clothingScrapingsSweat, skin, blood, tissueSweat, hair, dandruffSweat, skinMucus, blood, sweat, semen, earwaxBlood, sweat, semen, vomitSalivaSalivaSalivaSkin, sweatSaliva, sweatSemen, vaginal or rectal cellsSweat, hair, semen, urine, saliva, dandruffBlood, tissueSalivaBlood, tissue, sweat(Source: National Commission on the Future of DNA Evidence, National Institute of Justice, “What Every Law Enforcement Officer Should Know about DNA Evidence,” Pamphlet (Washington, DC: U.S. Department of Justice).DNA TECHNOLOGIESPolymerase Chain Reaction (PCR) takes small DNA samples and reproduces many copies for analysisShort Tandem Repeats (STRs) are smaller pieces of the DNA ladder that can be reproduced using PCRThe PCR-STR Process accelerates the analysis and typing of DNA7-12DATABANKING AND CODIS Today, all U.S. jurisdictions have legislation requiring the data banking of DNA evidence of convicted offendersIn addition to individual-jurisdiction data banking, there is a national investigation support database, developed by the FBI, called CODIS (COMBINED DNA Index System)CODIS is used in the national, state and local index-system networks to link typing results from unresolved crimes with cases in multiple jurisdictionsCODIS can also be used to link persons convicted of offenses specified in the data-banking laws passed by the jurisdictions7-13FORENSIC IDENTITY TESTDNA may be used to:Match victims or suspectsEliminate suspectsRelease persons wrongly convicted7-14(Courtesy San Bernardino County, California, Sheriff’s Department)TRADITIONAL FINGERPRINT IDENTIFICATION AND COMPARISONIn the past fingerprints taken from crime scenes have been classified, filed and searched according to the Henry SystemThe searches of fingerprints from scenes against a Henry System file are very labor-intensiveTechnological advancement since the 1970s have allowed the creation of an automated fingerprint identification process7-15AUTOMATED FINGERPRINT IDENTIFICATION SYSTEM (AFIS)In the early 1970s, the FBI and the National Bureau of Standards conducted feasibility research for establishing an automated fingerprint identification processAFIS allows law enforcement agencies to conduct comparisons of applicant and suspect fingerprints with literally thousands or millions of file prints in a matter of minutes7-16(a)AUTOMATED FINGERPRINT IDENTIFICATION SYSTEM (AFIS) (cont'd)AFIS has two major dutiesFirst is performing the functions of classifying searching and matching printsSecond is the storage and retrieval of fingerprints dataIn July 1999, law enforcement agencies began to have access to the FBI’S Integrated Automated Fingerprint Identification System (IAFIA), a national on-line fingerprint and criminal history database with identification and response capabilities7-16(b)AFIS FINGERPRINT COMPARISONLatent prints can be searched against a file of 500,000 prints in one half hourThe system produces a list of possibles called a candidate listFurther determinations are made by a qualified fingerprint examiner7-19(Source: Courtesy Dallas Police Department)INTEGRATED AUTOMATED FINGERPRINT IDENTIFICATION SYSTEM (IAFIS)The system was established by the FBIThis is a national on-line system with:Fingerprint and criminal history databasesIdentification and response capabilitiesLocal law enforcement began to access the system in 19997-18(b)INTEGRATED AUTOMATED FINGERPRINT IDENTIFICATION SYSTEM (IAFIS) (cont'd)The local police agency must have a live-scan fingerprint terminal. The agency may then:Scan an arrestee's prints and mug shotsElectronically transmit the prints, mug shots and personal information to their state's network for fingerprint checksThe state agency then transmits the same information to the FBI fingerprint repository for matches7-18(b)NATIONAL INTEGRATED BALLISTIC INFORMATION NETWORK PROGRAM (NIBIN)A joint program of the Bureau of Alcohol Tobacco and Firearms (ATF) of the Treasury Department and the FBI in the Department of JusticeThe NIBIN integrates all the elements of Ceasefire and Brasscatcher, both former ATF programs and Drugfire, an FBI programAs each fingerprint is different, a firearm leaves unique identifiable characteristics on expended ammunitionNIBIN compares images of ballistic evidence, both projectiles and casings, obtained from crime scenes and recovered firearms7-19ATF FORENSIC SCIENCE LABORATORIES These laboratories, in addition to analyzing alcohol and tobacco samples, conduct forensic examination in support of the bureau's explosives, bombing and arson, and illegal-firearm-trafficking investigations, along with major case investigations of state and local authoritiesEvidence collected at crime scenes of suspected arsons is examined to identify accelerants, incendiaries, and incendiary-device componentsThe bureau has four National Response Teams that respond to major bombings and arson disasters, nationally and internationally7-20(a)ATF FORENSIC SCIENCE LABORATORIES (cont'd) The ATF forensic labs also conduct:Comparative trace evidence examinationsQuestioned document examinationsFingerprint, firearm and tool-mark examinations7-20(b)THE FBI CRIME LABORATORYThe FBI crime laboratory is one of the largest and most comprehensive forensic laboratoriesIt provides services to state and local law enforcement without chargeExamples of lab services include:Microscopic examinationsChemical examinationsMineralogy examinations7-21(a)THE FBI CRIME LABORATORY (cont'd)Firearms examinationTool mark examinationsExplosives examinationsMetallurgical examinationsHandwriting and document examinationsChemical, biological and nuclear hazards examinations7-21(b)