Forensic Science An Introduction Forensic Science In its

Forensic Science: An Introduction

Forensic Science In its broadest definition it is the application of science to law l Applies to the knowledge and technology of science for the definition and enforcement of such laws l Definition: the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system l

Sciences involved Chemistry l Biology l Physics l Geology l Forensic pathology l Forensic psychology l Forensic Odontology l

History of Forensic Science Sir Arthur Conan Doyle: fictional character Sherlock Holmes had a great influence on popularizing the study of crime scenes l Holmes was the first to apply the principles of serology (blood typing and analysis), fingerprinting, firearm identification and document examination l l First book in 1887 “A Study in Scarlet”

Important People l Mathieu Orfila (1787 -1853) father of forensic toxicology; detection of poisons and their effects l Alphonse Bertillon (1853 -1914) scientific system for personal identification; taking body measurements as a means of distinguishing people; father of criminal identification

Important People l Francis Galton (1822 -1911) study of fingerprints and developed method for classifying them for filing l Karl Landsteiner in 1901 discovered ABO blood types l Leone Lattes (1887 -1954) devised a procedure for determining blood group of a dried bloodstain

Important People l Calvin Goddard (1891 -1955) comparison microscope to identify bullets l Albert Osborn (1858 -1946) document examination l Walter Mc. Crone (1916 -2002) known as the world’s preeminent microscopist; instructor, and author

Important People l Hans Gross (1847 -1915) Austrian judge who described the application of scientific disciplines to the field of criminal investigation. l Zoology, l botany, anthropology, fingerprinting Edmond Locard (1877 -1966) founder and director of the Institute of Criminalistics at the University of Lyons; workable crime lab

Important People l Edmond Locard: l Locard’s Exchange Theory: the exchange of materials between two objects that occurs whenever two objects come into contact with one anther l Locard believed every criminal can be connected to a crime by dust particles carried from the crime scene

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

4 Federal Crime Labs l l FBI: largest crime lab DEA Drug Enforcement Agency: analysis of drugs seized in violation of federal laws for production, sale and transportation of drugs ATFE 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 evidence U. S. Postal Inspection Services: maintains lab concerned w/criminal investigations relating to the postal service

Crime Lab Services Basic Services l Photography l Physical Science l Biology/DNA l Firearms l Document Examination Optional Services l Toxicology l Latent Fingerprint l Polygraphy l Voice Analysis l l Forensic Psychiatry Forensic Odontology Forensic Engineering Forensic Computer and Digital Analysis

What Forensic Scientists Do l Analyze physical evidence l Use l Determine admissibility of evidence l Frye l scientific methods v US (1923) – general acceptance Judge scientific evidence l Daubert case (1993) – trial judge is gatekeeper Provide expert testimony l Furnish training l

Physical Evidence Anything physical objects that can link a crime to its victims or to suspects. l Has to be collected from crime scene l Must be relevant to the crime l Requires the collector to understand what the capabilities and limitations of the crime lab are l

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

Arriving at the Crime Scene Secure and isolate the crime scene l Determine boundaries of crime scene and priorities for evidence collection l Rough sketch l Finished sketch l Photograph l Videotaping l Notes l

Collecting Evidence Conduct a systematic search for evidence; be unabiased and thorough. l Field technicians l What to look for depends on the crime and what specific locations of the crime scene would most likely be affected l Microscopic or massive objects l Collect carriers of possible evidence l Vacuum or sweeping collected l

Packaging of Evidence Prevent any changes from occurring (contamination, breakage, evaporation, bending, loss) l Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possible l Package evidence separately l

Tools for Collecting Evidence Forceps l Evidence envelopes and pill bottles l Swabs l Special concerns (mold, evaporation) l Various light sources l Latent fingerprints l Mobile crime labs or better yet crime scene search vehicle l

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

Submission of Evidence Standard/reference samples l Substance controls l Evidence submission form will detail the evidence collect and particular type of examination/analysis requested. l Lab tech not bound by requests l

Common Types of Evidence l l l Common Types of Evidence Blood, semen, and saliva Documents Drugs Fibers Fingerprints Firearms and ammunition Glass Hair Impressions Organs and physiological fluids l l l l l Paint Petroleum products Plastic bags Plastic, rubber, and other polymers Powder residues Serial numbers Soil and minerals Tool marks Vehicle lights Wood and other vegetative matter

Examination of Physical Evidence l Identification l l Determining the identity of a substance with a near absolute certainty while ruling out other substances Comparison l l l Comparing 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 Evidence l Assessing the values of evidence l l Class characteristics of evidence is valuable in corroborating events. Multiple class evidence can lead to a high level of certainty of origin Cautions 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 Databases l l l l One-on-one comparison requires a suspect Computerized databases help link evidence to people Fingerprint databases – IAFIS DNA database – Co. DIS Ballistics database – IBIS Automative Paint database – PDQ Shoeprint database - SICa. R