Lasley & Guskos, Criminal Investigation: An Illustrated Case Study Approach 1ed • Chapter 8 • INVESTIGATION AND THE FORENSIC SCIENCES Class Name,Instructor Name Date, Semester
CHAPTER OBJECTIVES • Explain what is meant by the term forensic sciences • Describe the role of the crime laboratory • Describe the various sections making up a crime laboratory • Describe how DNA analysis is used in criminal investigation • Be familiar with types of forensic sciences used outside thecrime lab
Learning Objectives After this lecture, you should be able to complete the following Learning Outcomes Explain what is meant by the term forensic sciences
FORENSIC SCIENCE Application of science to the law History of Crime in America 5
Frye & Daubert Tests • Frye test: • Frye v. US (1923) • Any science is recognized by a court as legitimate if it is accepted by a relevant scientific discipline (general acceptance standard) • Daubert test: • For a court to recognize forensic science it must: • Be testable • Establish error rates • Peer reviewed • Accepted by experts (scientific evidence standard)
FORENSIC SCIENTISTS CRIMINALISTS Perform analysis of crime scenes Work for the prosecution and can work privately for the defense Forensic Scientists 7
Learning Objectives After this lecture, you should be able to complete the following Learning Outcomes Describe the various sections making up a crime laboratory
Learning Objectives After this lecture, you should be able to complete the following Learning Outcomes Describe the role of the crime laboratory
Crime Lab Sections • Toxicology—affects, both physical and behavioral that poisons have on the body • Fingerprint identification—processing of fingerprints, use of AFIS and IAFIS to match prints, ACE-V (analysis, compares, evaluates, verification) • Serology—analyses blood stains and performs blood testing (blood types O, A, B, AB) • Arson and Explosives—fire and explosive evidence, examine burnt, destroyed objects from explosions
Crime Lab Sections • Firearms and Tool Marks—examinations to determine class and individual characteristics of tools and firearms, NIBIN • Trace evidence—hairs, fibers, glass fragments, paint chips, and other materials in minute sizes are analyzed in this section • Questioned documents—false documents that assist in financial crimes, identify paper, inks, writing styles, etc.
Learning Objectives After this lecture, you should be able to complete the following Learning Outcomes Describe how DNA analysis is used in criminal investigation
nDNA Considered a genetic fingerprint which contains codes and instructions for the body to create and sustain itself Genetic Fingerprint 20
Analysis methods • nDNA: PCR is the method of choice • Removal of DNA strands from cells, coding can begin once separated • mtDNA: • An addition to the nDNA method; the shaft region of all body hairs is tested and can yield results without skin cells attached
CODIS & The future of DNA • FBI DNA database system • Combined DNA Index System • Profiles of adults and juveniles • The Innocence Project (1992) • DNA exonerated some inmates based on this scientific method
Learning Objectives After this lecture, you should be able to complete the following Learning Outcomes Be familiar with types of forensic sciences used outside the crime lab
CHAPTER SUMMARY Forensic science is the application of science to the law. Although virtually any forensic science can be applied to the practice of investigation, the law dictates which forensic sciences can be used to present evidence in a legal proceeding. Crime labs conduct scientific analyses on physical evidence obtained from crime scenes, victims, and suspects. Many of the functions carried out by crime labs include performing presumptive and confirmatory testing of suspected, yet unknown, illegal substances and materials. Specialized testing is also conducted to class and individualize evidence in support of investigations, legal proceedings, and trials. Crime lab sections include toxicology, fingerprint ID, serology, arson and explosives, firearms and tool marks, trace evidence, questioned documents, and DNA analysis.
CHAPTER SUMMARY DNA can be acquired from a variety of sources within the human body, including white blood cells, skin cells (nDNA), and hair (mtDNA). In the analysis of nDNA, which can be individualized in the form of a human genetic fingerprint, specific characteristics of locations on DNA strands are compared for differences. This generates a DNA profile, which can be used to positively identify offenders or exclude suspects. mDNA, which is obtained from hair or the mitochondria of cells, cannot be used to positively identify offenders, but is useful for excluding suspects. Branches of the forensic sciences practiced by experts outside the crime lab include forensic pathology, forensic anthropology, forensic psychology and psychiatry, forensic entomology, and digital forensic science.