1. Analyzing Fibers Forensic Science

2. Fibers Material composing fabrics and garments
Two types: Man-made and Natural

3. Natural Fibers Derived completely from plant or animal sources
Identified by microscopic examination of color and morphology of fiber
Most prevalent is cotton

4. Microscopic Examination of Cotton
Under microscope, the cotton looks like twisted ribbon or collapsed and twisted tubes. These twists are called convolutions.

5. Man-Made Fibers Fibers created from natural or synthetic polymers
Dates back to 1911 with rayon and 1939 with nylon
Polymers: chains of regular and repeating atoms

6. Microscopic View of Polyester
Smooth fibers with regular diameter. Diameter generally ranges from micrometers. The un-dyed fabric is usually off white and transparent.

7. Comparison and Identification of Fibers
Most important is the ability to trace the origin of the fibers
Only if pieces completely fit together can a definite origin be determined
If cannot fit together, the fibers must be compared side-by-side with standard/reference samples

8. Comparison and Identification of Fibers (cont’d)
First microscopically compare fibers for diameter and color
Look for other morphological details like striations or pitting
Use visible light microspectrophotometer to analyze colors of fibers for comparison

9. Collection and Preservation of Fiber Evidence
Know potential carriers of fiber evidence
Collect and package evidence in separate paper bags
Fold blankets, carpets and rugs to prevent loss of evidence
Cover car seats with polyethylene sheets