Fibers and hair can provide strong corroborating evidence to place a perpetrator at a crime scene. Fibers are made of twisted or bonded filaments and can be natural like cotton or synthetic like nylon. Their properties like color, diameter, and chemical composition can be analyzed and compared to known samples. Hair is also a type of fiber but usually cannot individually identify a person without DNA. Hair morphology like the root, medulla, and cuticle can provide clues about species and whether a hair was forcibly removed or naturally shed.

1. Fiber and Hair Evidence

2. Fibers most often used as class evidence can provide strong corroborating evidence to place perpetrator at crime scene

3. Fibers fiber many filaments twisted or bonded together to form thread or yarn filament single strand of material of indefinite length

4. Fibers can be natural silk, wool, mohair, cashmere, angora, cotton, linen, jute, sisal, hemp, ramie, asbestos, fiberglass, rayon can be artificial or synthetic acrylic, aramid, nylon, olefin, spandex, polyester, modacrylic

5. Fibers physical properties color chromatography of dyes polarization with light blend and /or weave diameter of fibers cross sectional shape

7. Fibers physical properties # of filaments density refractive index refraction is the bending of light waves due to a change in the velocity fluorescence

8. Fibers chemical properties burning tests (oxidation) analysis ash, behavior in and out of flame, odor thermal decomposition pH, residue and component chemicals chemical decomposition treatment with various strong acids, bases and solvents

9. Fibers many of these tests would be made between the unknown and reference samples taken at scene reference samples taken from individuals involved at scene exemplars – scientific standards accepted widely usually found in databases

10. Fibers many of these tests would be made between the unknown & reference samples taken at scene reference samples taken from individuals involved at scene exemplars – scientific standards accepted widely usually found in databases

11. Hair considered a type of fiber not able to individualize unless DNA is present w/o DNA, it can provide strong corroborative evidence for placing an individual at a crime scene

12. Hair morphology root in follicle shaft cuticle cortex medulla tip/end

13. Hair morphology root in follicle shaft cuticle cortex medulla tip/end

14. Hair morphology - shaft cuticle scale structure covering the exterior of the hair scales always point to tip of hair scale pattern often used for species identification

15. Hair morphology - shaft cortex main body of the hair shaft pigment giving hair its color is embedded in the cortex lack of pigment = gray or white number, shape and distribution of pigment granules can be used to narrow down class

16. Hair morphology - shaft medulla may appear dark or translucent depending on substances inside can be continuous, interrupted or fragmented also used to identify to species medullary index measures diameter of medulla relative to diameter of hair shaft humans usu. less than 1/3, animals usu. more than ½

17. Hair morphology - root located in hair follicle of skin three stages of growth anagen phase: major growth catagen phase: intermediate telogen phase: mature hair – will “fall” out

18. Hair morphology - root telogen naturally shed hairs, such as a head hair dislodged through combing, display undamaged, club-shaped roots

19. Hair morphology - root anagen or catagen a hair forcibly removed from the scalp will exhibit stretching and damage to the root area forcibly removed hairs may have tissue attached may contain DNA

20. Hair other root is embedded in follicle which is in equalized with the blood supply anything taken into the body is distributed into growing hair (drugs, poisons) esp. metals like Hg, As, Pb time frame can be established as hair grows at a fixed rate