1. Fiber Evidence Value?

2. Fiber Sources Natural Synthetic or Manufactured Plant sources
Animal Sources
Rayon (1911)
Nylon (1931)
Dacron
Polyester

3. Polymer The basic chemical structure of all synthetic fibers
All polymers consist of repeating units called monomers
Polymers are made by linking many monomers together.

4. Identification and Comparison
The value of fiber evidence lies in the criminalists ability to trace its origin

5. Torn Garments or Fabrics?

6. Physical Properties
Crimp
Pliability
Resilience
Perform “Burn test”

7. Just a Few Small Fibers?
Comparison Microscope

8. Morphology and Cross Sectional Shape
Trilobal and Multilobed – Some trilobal examples appear below
Round and dumbbell shape
Some round examples appear below

9. Determine Chemical Composition of the Dyes
The Next Step
Determine Chemical Composition of the Dyes

10. Use a Visible Light Microspectrophotometer
A Microscope Combined With a Computerized Spectrophotometer

11. Chromatography Can Be used to Analyze Dyes
Thin Layer Chromatography is the method of choice

12. All Techniques Require a Side-by-Side Comparison The Value of the Techniques Lies in the Ability of The Analyst to Narrow a Fiber’s Origin to a Limited Number of Sources