1. Physical Evidence Chapter 3

2. Types of Physical Evidence Blood, semen, saliva Document Drugs Explosives Fibers Fingerprints Firearms and ammunitions Glass Hair http://www.youtube.com/wat ch?v=Wo- VO4sAJI4&feature=related http://www.youtube.com/wat ch?v=Wo- VO4sAJI4&feature=related Impressions Organs and fluids Paint Petroleum products Plastic bags Plastic, rubber, polymers Powder residues Serial numbers Soil and minerals Tool marks Vehicle lights Wood and vegetative matter

3. Analyzing Physical Evidence Identification—process of identifying the physical or chemical identity of an unknown substance Comparison—process of deciding whether two or more substances have a common origin

4. Identification Check for presence of illicit drugs Presence of gasoline in explosives Step 1—use of standard testing procedures Step 2—do as many tests as necessary to exclude other possibilities

5. Comparison Subject suspect specimen and known standard to same battery of tests Step 1—Test various qualities of test and standard subjects Step2—Draw conclusions about the origins of the specimens

6. Comparison testing continued Individual characteristics— properties of evidence that can be attributed to a single source with a high degree of certainty Class characteristics— properties of evidence that can only be associated with a group and never with a single source

7. Value and Limitations of Physical Evidence Value – Needs to corroborate data without introducing error or bias – Collective class evidence can be very conclusive in courtroom Limitations – Jury or judge determines value in courtroom – No two things are completely identical if all exhaustive tests are looked at

8. Forensic Databases Suspects can be linked to a crime through comparative analysis Requires suspect to match to known standards Link information of all 50 states and other nations

9. Fingerprint Database Integrated Automated Fingerprint Identification System (IAFIS), national fingerprint system maintained by the FBI and launched in 1999 Comparison search from anywhere in US can be done in just minutes Other countries have similar national systems http://www.youtube.com/w atch?v=pSwH-51OFEQ http://www.youtube.com/w atch?v=pSwH-51OFEQ

10. DNA Database Combined DNA Index System (CODIS) by FBI became fully operational in 1998 National collection of DNA from two sources: forensic index and offender index Forensic index—DNA collected from physical evidence Offender index—DNA from past offenders http://www.youtube.com/w atch?v=Trdu_s_XzRo http://www.youtube.com/w atch?v=Trdu_s_XzRo

11. Other Databases National Integrated Ballistics Information Network (NIBIN) allows comparison of markings made by bullets and firearms International Forensic Automotive Paint Data Query (PDQ) contains data for color and paint information for original automotive paints Shoeprint Image Capture and Retrieval (SICAR) is not government regulated—it is used to compare and identify crime scene shoeprints

12. Crime Scene Reconstruction Method used to support likely sequence of events at crime scene by observing and evaluating physical evidence and statements made by those involved with the incident http://www.youtube.com/watch?v=H S67MGEaGRM http://www.youtube.com/watch?v=H S67MGEaGRM Involves several personnel – Medical Examiners—cause of death, movement of body, etc – Criminalistics—use lasers to find path of gunfire, angles, positions of shooters, etc. – Law Enforcement Personnel – http://www.youtube.com/ watch?v=e3E2AMgDf5Y http://www.youtube.com/ watch?v=e3E2AMgDf5Y