1. Fiber Analysis

2. Crimes involving fiber evidence
Homicide
Battery
Sexual Battery
Hit and Run
Burglary

3. Types of Fibers
Natural=
Derived from animal (Hair/Fur) or plant

4. Cotton
Ribbon-like with twists and hollow
Video

5. Silk
Fibers are smooth and naturally transparent

6. Wool
Appear round with scale-like markings
Video

7. Other Natural Fibers
Goat
Mohair, cashmere
Camel
Llamas
Alpacas
Mink

8. Other Natural Fibers
Rabbit
Beaver
Muskrat

9. Types of Fibers Man-made=
Fibers derived from natural or man-made polymers

10. What is a polymer?
A substance composed of a large number of atoms (macromolecules) arranged in repeating units of monomers

11. What is a monomer?
Basic unit of a polymer

12. Types of Man-made Fibers
Regenerated Fibers:
Man-made but from natural sources (cotton or wood pulp to get cellulose)
Ex. Rayon (First Manufactured Fiber)
Acetate
Triacetate

13. Rayon
Soft, absorbent and dries quickly

14. Acetate
Luxurious appearance, soft feel, fast drying

15. Triacetate

16. Types of Man-made Fibers
Regenerated Fibers:
Ex.
Fiber Optics

17. Types of Man-made Fibers
Synthetic Fibers=
Made solely of chemicals
Ex. Nylons
Polyesters
Acrylics

18. Nylon
Strong, nonabsorbent, lustrous

19. Polyester
Strong, Quick drying, Wrinkle-free

20. Acrylics
Soft, warm, wool-like, quick-drying

21. Fiber Analysis (Easy)
Jig-saw puzzle method

22. Fiber Analysis (Hard) Single Fibers Microscopic Comparative Studies
Microscopic comparisons of color
Microscopic comparisons of diameter
Examination for lengthwise striations
Examination for pitting (use Titanium dioxide to deluster fiber)
Look at cross-sectional shape

23. Color
Cross-sectional shape
striations

24. Color Analysis of Fibers
Compare dyes of two different fibers
Use Thin-layer Chromatography

25. Refractive Index of Fibers
Look for absence of Becke Line

26. Infrared Spectrophotometry and Fibers
Case Study:
1979 Dr. Jeff MacDonald convicted of the murder of wife and children
Claimed intruders committed act
11 years pass

27. Infrared Spectrophotometry and Fibers
Case Study
Analyzed wig fibers that were on a household brush (Claimed intruders wore wigs)
FBI used infrared spectrophotometry to show that the fiber in brush matched a product of his wife

29. Other Tests on Fiber
Flame Test
Solubility Test
Stain Test

30. Fiber Collection
Identify, and preserve potential carriers of fibers

31. Collection Package Cloths Weapons Rugs Bedding
Take adhesive tape-lifts from body