1. 2009©Forensic Science Today Fibers Collection, Testing and Determination of Uniqueness Deedrick, D. W. Hairs, fibers, crime, and evidence, Forensic Science Communications [Online]. (July 2000). Available: http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm. http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm

2. 2009©Forensic Science Today Types of Fiber Natural- –Any fiber that comes from plant or animal sources, examples? Image of cotton fibers. Deedrick, D. W. Hairs, fibers, crime, and evidence, Forensic Science Communications [Online]. (July 2000). Available: http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm.http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm

3. 2009©Forensic Science Today Types of Fibers Cont’d Synthetic- –Any fiber that is made in a laboratory, examples? Image of nylon. Deedrick, D. W. Hairs, fibers, crime, and evidence, Forensic Science Communications [Online]. (July 2000). Available: http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm.http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedrick.htm

4. 2009©Forensic Science Today Testing Fibers are generally identified by type of cloth and color by Physical Properties –Burn test –Melting test –Solubility –Optical properties –Dye identification

5. 2009©Forensic Science Today Burning and Melting Tests Place the fiber in a flame and record the results. Heat the fiber on a hotplate and record the results. Changes in physical properties: color, smoke, smell, etc.

6. 2009©Forensic Science Today Solubility Test What is it soluble in? –Strong base –Strong acid –other

7. 2009©Forensic Science Today Optical Properties These are the tests that are currently used to identify fibers. Behavior in –visible, –IR, –UV and –polarized light Image from www.usgs.gov/

8. 2009©Forensic Science Today Identification of Dye Thin Layer Chromatography –Separates molecules based on the affinity to the surface they are placed on versus their solubility in the solvent they are being dissolved in –Low solubility in solvent and high adhesion to the surface--- does not go very far

9. 2009©Forensic Science Today Image from www.dps.state.ia.us

10. 2009©Forensic Science Today Comparison? How is the fiber from a scene compared to fiber from a known source? –All the characteristics found on the known fiber and the questioned fiber must be identical. What does it mean to say they are similar fibers? –Class –Individual

11. 2009©Forensic Science Today Characteristics High probability of linkage with only one individual. One of a kind? unusually made fiber made in very small amount with unusual dye Consistent with a group Individual Class

12. 2009©Forensic Science Today Fiber Collection Cellophane tape into Petri dish or Vacuuming Choose container that will prevent loss Label and Seal

13. 2009©Forensic Science Today Comparison of Fibers Fibers from victim’s fingernail to known sample from suspect’s sweater.

14. 2009©Forensic Science Today Control Samples From victim & suspects’ homes and vehicles Uncontaminated Large enough to do testing needed