13 Forensic Science Powerpoint Chapter 13 The Forensic Laborat

Chapter 13Chapter 13CRC Press: Forensic Science, James CRC Press: Forensic Science, James

and Nordby, 3rd Editionand Nordby, 3rd Edition 11

Forensic ScienceForensic ScienceAn Introduction to Scientific and An Introduction to Scientific and

Investigative TechniquesInvestigative Techniques

Stuart H. James and Jon J. NordbyStuart H. James and Jon J. Nordby

22Chapter 13Chapter 13CRC Press: Forensic Science, James CRC Press: Forensic Science, James

and Nordby, 3rd Editionand Nordby, 3rd Edition

Chapter 13Chapter 13

The Forensic LaboratoryThe Forensic Laboratory

Chapter Author: Linda R. NetzelChapter Author: Linda R. Netzel

Presentation created by Greg Galardi, Peru, NebraskaPresentation created by Greg Galardi, Peru, Nebraska

Edited by Stuart H. James, Fort Lauderdale, Florida andEdited by Stuart H. James, Fort Lauderdale, Florida and

Dan Mabel, Richmond, VirginiaDan Mabel, Richmond, Virginia



Forensic Science in the Forensic Science in the LaboratoryLaboratory

Forensic laboratory has two purposes:Forensic laboratory has two purposes:• Responsible for analysis of evidenceResponsible for analysis of evidence• Involved in all aspects of evidence Involved in all aspects of evidence

recognition, collection, and preservationrecognition, collection, and preservation• Must insure law enforcement officers, Must insure law enforcement officers,

investigators, attorneys, judges and juries investigators, attorneys, judges and juries are educated in understanding the are educated in understanding the parameters which surround collection and parameters which surround collection and testing of evidencetesting of evidence



Quality AssuranceQuality Assurance

Forensic laboratories have quality Forensic laboratories have quality assurance programs to:assurance programs to:

• Ensure reported results are scientifically Ensure reported results are scientifically validvalid

• Opinions are based only upon results Opinions are based only upon results deemed reliabledeemed reliable



Quality AssuranceQuality Assurance

• Q.A. programs may also have staff Q.A. programs may also have staff education requirements, peer review of education requirements, peer review of results, specific case file results, specific case file documentation, distribution of reports, documentation, distribution of reports, auditing of testimony, evidence auditing of testimony, evidence handling and laboratory securityhandling and laboratory security

• Proficiency tests are simulated cases Proficiency tests are simulated cases which assist criminalists in determining which assist criminalists in determining their error ratestheir error rates



Staffing IssuesStaffing Issues

• Forensics is a general term which may Forensics is a general term which may be applied to a number of disciplines, be applied to a number of disciplines, such as anthropology or odontologysuch as anthropology or odontology

• Criminalistics applies the application of Criminalistics applies the application of chemistry, biology, or physics to chemistry, biology, or physics to evidence analysis and addresses crime evidence analysis and addresses crime scene investigation and reconstructionscene investigation and reconstruction



Staffing IssuesStaffing Issues

Applicants for positions in a forensic Applicants for positions in a forensic laboratory can expect:laboratory can expect:

• Thorough background investigationThorough background investigation• Polygraph examinationPolygraph examination• History of illegal drug use and screeningHistory of illegal drug use and screening• Driving record checkDriving record check• Employment and residential history reviewEmployment and residential history review



Accreditation and CertificationAccreditation and Certification

• American Society of Crime Laboratory American Society of Crime Laboratory Directors focuses on accreditation of Directors focuses on accreditation of laboratorieslaboratories

• Laboratories are accredited for 5 yearsLaboratories are accredited for 5 years• Accreditation includes comprehensive Accreditation includes comprehensive

inspection, interviews with staff, review inspection, interviews with staff, review of written procedures and quality of written procedures and quality assurance programsassurance programs



Accreditation and CertificationAccreditation and Certification

• Criminalists may be awarded individual Criminalists may be awarded individual certification by the American Board of certification by the American Board of Criminalistics or the International Criminalistics or the International Association of IdentificationAssociation of Identification

• To maintain certification, individuals To maintain certification, individuals must complete professional activities, must complete professional activities, attend or provide training, write in attend or provide training, write in scientific journals attend meetings, and scientific journals attend meetings, and complete proficiency testingcomplete proficiency testing



Types of LaboratoriesTypes of Laboratories

• Government Laboratories – FBI, ATF, Government Laboratories – FBI, ATF, DEA and USPO all have laboratoriesDEA and USPO all have laboratories

• Private Laboratories – may provide Private Laboratories – may provide forensic testing to police and or forensic testing to police and or defendants. Greatest contribution by defendants. Greatest contribution by private labs is retesting evidence private labs is retesting evidence examined by government or public labexamined by government or public lab



Qualifications of a Forensic Qualifications of a Forensic ExaminerExaminer

To be a forensic examiner:To be a forensic examiner:• Possess a baccalaureate degree in natural Possess a baccalaureate degree in natural

science: emphasis in physics, biology, science: emphasis in physics, biology, chemistry or forensic sciencechemistry or forensic science

• On the job training will assist entry level On the job training will assist entry level criminalists in gaining necessary skills criminalists in gaining necessary skills and knowledge for career developmentand knowledge for career development

• DNA technical managers must have a DNA technical managers must have a Master’s Degree according to D.A.B.Master’s Degree according to D.A.B.



Qualifications of a Forensic Qualifications of a Forensic ExaminerExaminer

• Criminalists should review research Criminalists should review research journals, especially the Journal of journals, especially the Journal of Forensic Sciences, to enhance their Forensic Sciences, to enhance their knowledgeknowledge

• Review of important historical work, by Review of important historical work, by Gross, O’Hara, Osterburg and Kirk are Gross, O’Hara, Osterburg and Kirk are viable sources to learning more about viable sources to learning more about the field of forensic sciencethe field of forensic science



Understanding the Role of the Understanding the Role of the CriminalistCriminalist

• Criminalists- provide investigative Criminalists- provide investigative leads through scientific evaluation of leads through scientific evaluation of physical evidence and crime scene physical evidence and crime scene reconstruction, report results and reconstruction, report results and conclusions of scientific evaluations, conclusions of scientific evaluations, and provide expert testimony and provide expert testimony

• Criminalists must be able to use their Criminalists must be able to use their own ability to ask questions and own ability to ask questions and investigate available informationinvestigate available information



Understanding the Role of the Understanding the Role of the CriminalistCriminalist

• Criminalists will serve as an educator Criminalists will serve as an educator for law enforcement, investigators, for law enforcement, investigators, attorneys, medical professionals, attorneys, medical professionals, judges and othersjudges and others

• Due to the rapid growth and change Due to the rapid growth and change within this field, criminalists must within this field, criminalists must constantly stay apprised of changes constantly stay apprised of changes through education and professional through education and professional seminarsseminars



Linking a Suspect to a Scene of Linking a Suspect to a Scene of a Crimea Crime

Reconstruction Evidence – provides Reconstruction Evidence – provides information about the events information about the events preceding, occurring during, and after preceding, occurring during, and after commission of a crimecommission of a crimeReconstruction includes:Reconstruction includes:• Observation by criminalistObservation by criminalist• Logic of criminalistLogic of criminalist• Experience of criminalistExperience of criminalist• Evaluation of witness statementsEvaluation of witness statements



Associative EvidenceAssociative Evidence

• Associative evidence is evidence that Associative evidence is evidence that can associate a suspect to a crime can associate a suspect to a crime scenescene

• Examples are: hair, fiber, blood, body Examples are: hair, fiber, blood, body fluids, paint, glass, firearms, fluids, paint, glass, firearms, fingerprints and other imprint evidencefingerprints and other imprint evidence



Associative EvidenceAssociative Evidence

Associative evidence can be divided Associative evidence can be divided into two categories:into two categories:• Class evidence- not considered unique, Class evidence- not considered unique,

examples such as rope fiber, carpet fiber, examples such as rope fiber, carpet fiber, glass, etcglass, etc

• Identification evidence – positively Identification evidence – positively provides for identification – blood, DNA, provides for identification – blood, DNA, semen, fingerprintssemen, fingerprints



Laboratory Sections, Analytical Laboratory Sections, Analytical Instruments and Specialized Instruments and Specialized

EquipmentEquipment

• Depending on the size of the laboratory, Depending on the size of the laboratory, there may be specializations for certain there may be specializations for certain aspects of evidence analysis within that aspects of evidence analysis within that laboratory, such as biological evidence, trace laboratory, such as biological evidence, trace evidence, fingerprint evidence, impression evidence, fingerprint evidence, impression evidence, firearm and tool mark evidence, evidence, firearm and tool mark evidence, questioned documents, chemical evidence questioned documents, chemical evidence and photographic evidenceand photographic evidence



Laboratory Evidence SectionsLaboratory Evidence Sections

• Biological evidence - identification and Biological evidence - identification and individualization of human tissuesindividualization of human tissues

• Includes DNA testing of semen, blood, Includes DNA testing of semen, blood, saliva and hairsaliva and hair

• Restriction Fragment Length Restriction Fragment Length Polymorphism (RFLP) was first method Polymorphism (RFLP) was first method used to analyze forensic DNA samplesused to analyze forensic DNA samples

• Polymerase chain reaction (PCR) is Polymerase chain reaction (PCR) is currently used by most laboratoriescurrently used by most laboratories




• Trace Evidence- defined as Trace Evidence- defined as microscopic physical evidencemicroscopic physical evidence

• Can encompass hair, body fluids, paint, Can encompass hair, body fluids, paint, fiber, plants , debris, cosmetics, etcfiber, plants , debris, cosmetics, etc

• Trace evidence must be carefully Trace evidence must be carefully collected since it can easily be collected since it can easily be contaminatedcontaminated




Methods of trace evidence collection:Methods of trace evidence collection:• VacuumingVacuuming• Hand pickingHand picking• Tape liftsTape lifts

Microscopes are the primary tool used Microscopes are the primary tool used during trace evidence analysisduring trace evidence analysis

Types of microscopes include compound Types of microscopes include compound light, polarizing light, phase contrast and light, polarizing light, phase contrast and comparison comparison




• Trace evidence analysis may involve Trace evidence analysis may involve use of spectrometers, such as the use of spectrometers, such as the Fourier transform infrared Fourier transform infrared spectrometry, which assists in spectrometry, which assists in providing chemical fingerprints of providing chemical fingerprints of inorganic and organic substancesinorganic and organic substances

• Scanning electron microscopes (SEM) Scanning electron microscopes (SEM) may also be utilizedmay also be utilized




Fingerprint Evidence - two aspects of Fingerprint Evidence - two aspects of fingerprinting available:fingerprinting available:• Latent printing- accomplished via chemical Latent printing- accomplished via chemical

methods, physical methods, lighting and methods, physical methods, lighting and photographic methodsphotographic methods

• Digital imaging of fingerprint methods is Digital imaging of fingerprint methods is being increasingly used to identify being increasingly used to identify fingerprints. Automated Fingerprint fingerprints. Automated Fingerprint Identification Systems (AFIS) are being Identification Systems (AFIS) are being usedused




• Impression Evidence - footwear and tire Impression Evidence - footwear and tire impressions are examples of evidence impressions are examples of evidence which may be examined in the which may be examined in the laboratorylaboratory

• Firearm Evidence - criminalist will Firearm Evidence - criminalist will examine fired bullets, cartridge examine fired bullets, cartridge casings, and shot shellscasings, and shot shells

• Impressions and markings are left on Impressions and markings are left on these when discharged from weaponthese when discharged from weapon




Firearms examiner will use:Firearms examiner will use:• Stereomicroscope – provides general Stereomicroscope – provides general

information about evidence and possibly information about evidence and possibly reveal trace evidencereveal trace evidence

• Comparison microscope – allows side by Comparison microscope – allows side by side comparison of projectiles and casingsside comparison of projectiles and casings

• Water tank is used to collect fired bullets, Water tank is used to collect fired bullets, which are compared to bullets form crime which are compared to bullets form crime scenescene




• Comparison of bullets will include Comparison of bullets will include review of striae, which are markings on review of striae, which are markings on a bulleta bullet

• Distance determinations by criminalists Distance determinations by criminalists are also made when a person claims are also made when a person claims self defenseself defense




• Impressions made by tools such as pry Impressions made by tools such as pry bars, screwdrivers, etc may also leave bars, screwdrivers, etc may also leave striation type markingsstriation type markings

• Impressions left by tools at crime Impressions left by tools at crime scene are cast, and when tool is scene are cast, and when tool is recovered, an impression is made by recovered, an impression is made by that tool and cast for comparison to that tool and cast for comparison to one from crime sceneone from crime scene

• Other evidence – paint chips, glassOther evidence – paint chips, glass




• Questioned documents are examined Questioned documents are examined through handwriting comparison, through handwriting comparison, alterations, obliterations, and erasuresalterations, obliterations, and erasures

• Exemplars are taken from possible Exemplars are taken from possible authors to compare to forged authors to compare to forged documentdocument

• Watermarks, copy machine marks, and Watermarks, copy machine marks, and other machines may also leave distinct other machines may also leave distinct marks for comparisonsmarks for comparisons




• Chemical evidencetesting for chemicals Chemical evidencetesting for chemicals available which caused arson, explosions, available which caused arson, explosions, blood alcohol determinations, and poison blood alcohol determinations, and poison testing may be donetesting may be done

• Most chemical tests start with a presumptive Most chemical tests start with a presumptive or spot test- a spot of the evidence is tested or spot test- a spot of the evidence is tested with a liquid and liquid turns a specific color with a liquid and liquid turns a specific color if that evidence is presentif that evidence is present

• GCMS, FTIR, spectrophotometry, x-rays, and GCMS, FTIR, spectrophotometry, x-rays, and SEM may be used for confirmation testingSEM may be used for confirmation testing

Technology

13 Forensic Science Powerpoint Chapter 13 The Forensic Laborat