Forensic Science: An Introduction

1. Forensic Science: An Introduction

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

3. Sciences involved • Chemistry • Biology • Physics • Geology • Forensic pathology • Forensic psychology • Forensic Odontology

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

5. Important People • Mathieu 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

6. Important People • Francis 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

7. Important People • Calvin Goddard (1891-1955) comparisonmicroscope to identify bullets • Albert Osborn (1858-1946) document examination • Walter McCrone (1916-2002) known as the world’s preeminent microscopist; instructor, and author

8. Important People • Hans 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

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

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

11. 4 Federal Crime Labs • 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

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

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

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

15. Physical Evidence • Crime 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

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

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

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

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

20. Chain of custody • Continuity of possession; every person who touched it must be accounted for • Standards 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

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

22. Common Types of Evidence Blood, semen, and saliva Documents Drugs Fibers Fingerprints Firearms and ammunition Glass Hair Impressions Organs and physiological fluids 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 Common Types of Evidence

23. Examination of Physical Evidence • Identification • Determining the identity of a substance with a near absolute certainty while ruling out other substances • Comparison • 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)

24. Significance of Physical Evidence • Assessing the values of evidence • 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.

25. Forensic Databases • One-on-one comparison requires a suspect • Computerized databases help link evidence to people • Fingerprint databases – IAFIS • DNA database – CoDIS • Ballistics database – IBIS • Automative Paint database – PDQ • Shoeprint database - SICaR