1. Hair, Fiber, and Textile Analysis
Chapters 3 & 4

2. Hair Importance in forensics first recognized in 1800s Trace evidence
Locard’s Principle of Exchange
Class evidence
Does not easily decompose (tough outer coating - keratin)
Physical characteristics offer clues about race
Chemical tests provide history of drug usage, toxins, heavy metals, nutritional deficiencies
DNA evidence can be obtained if follicle attached (individual evidence)

3. Structure & Function of Hair
Regulate body temperature, decrease friction, protect against sunlight, act as a sense organ
Two parts: follicle and shaft
Follicle
Papilla at end – network of blood vessels that supply nutrients to the hair
Papilla surrounded by bulb – sebaceous gland associated with bulb (secretes oil)
arrector pilli muscle attached to bulb (causes hair to stand upright)
Nerve cells wind around follicle (stimulate muscle)
Shaft
Composed of protein keratin (produced in skin) – provide strength
Three layers: cuticle (outer layer), cortex (between), medulla (middle)

4. Stratified Squamous Epithelium (keratinized)
Dense CT
hypodermis

5. Hair anatomy Produces hair; root is enclosed in follicle Growth zone
Shaft extends from the surface of the scalp/skin
Hair anatomy
Produces hair; root is enclosed in follicle
Bulk of hair shaft is dead material and almost entirely protein (cortex most heavily keratinized)
Growth zone
Blood supply

6. Cuticle Transparent outer layer of the hair shaft
Made of scales that overlap one another and provide protection for inner layers of hair
Scales point from proximal end to distal end
Direction shows younger and older ends of hair
Useful for drug, metal, and toxin analysis
Human

7. Cortex Contains pigment granules
Melanin
Distribution of pigment varies from person to person
Determine hair color or processed hair color

8. Medulla Center of the hair
Five groups depending on appearance of medulla

9. Hair Types Distinguished by cross-sectional shape
Head hair: circular or elliptical
Eyebrows and eyelashes: circular with tapering ends
Beard and mustache hair: thick and triangular
Underarm hair: oval or triangular (depending on whether it has been recently shaved)
Auxiliary or body hair: oval or triangular (depending on whether it has been recently shaved)
Pubic hair: oval or triangular

10. Other Considerations Treated hair Racial Differences
Can estimate when last treated if entire hair recovered from scene
Growth rate: 1.3 cm per month (0.44 mm per day)
Example: unbleached root region measured 2.5 cm, then 2.5 cm divided by 1.3 cm per month equals approximately 1.9 months or 7 weeks
Racial Differences
Broad characteristics that are only generalities, may not fit for every individual
Mongoloid (Oriental, American Indian) – cross section is rounded
Caucasoid (American, European, Mexican, and Middle Eastern) – cross section is oval
Negroid (African descent) – cross section is flat

11. Racial Differences

13. What can hair not usually tell us?
What Can Hair Tell Us?
Human or animal
Part of the body
Color
Disease, mistreatment
What can hair not usually tell us?
Age (only lanugo that newborns are born with)
Gender (only if can do DNA analysis on follicular cell)
Race (only if fairly pure ancestry)

14. Human vs. Animal Hair Several differences Pigmentation pattern Medulla
Humans: denser toward cuticle
Usually one color along the length
Animals: denser toward medulla
Solid masses called ovoid bodies
Can change abruptly in banded pattern
Medulla
Humans: smaller, medullary index -.33 or less
Animals: much larger, always continuous, medullary index 0.5 or greater
Cuticle
Humans: imbricate scale pattern
Rodents and bats: coronal pattern
Cats, seals, mink: spinous pattern

15. Medullary Index
ratio of the diameter of the medulla to the diameter of the entire hair – animals have larger MI!

18. Collecting Hair Evidence
Plucking, shaking, scraping surfaces, tape, vacuum with filter
Determine whether the hair is human or animal via compound microscope
Compare sample with hair taken from six major body regions of the victim or suspect(s)
Comparison microscope

19. Testing for Substances
Chemicals that the skin absorbs or that are ingested can be incorporated into hair
Hair dissolved in organic solvent that breaks down keratin and releases substances
Forensic chemist can perform tests for the presence of various substances – evidence of poisoning or drug use
Can establish a timeline for exposure to poisons or other toxins using growth rate of hair and distance of toxin from root
Neutron activation analysis: identifies up to 14 different elements in a single 2 cm long strand of human hair
Probability of two individuals having the same concentration of nine different elements is about one in a million

20. Hair Follicle Follicular tag: entire hair follicle present
Can occur if hair is forcibly removed
DNA analysis can be performed on hair-follicle cells
Individual evidence (hair shaft analysis is class evidence)
Typically only do DNA testing if microscopic match between suspect and hair sample is found

21. Case Study Napoleon Bonaparte
Declared himself emperor of France in 1804
Defeated and exiled to St. Helena
Controversy over death by stomach cancer vs. murder by arsenic (found in hair when tested in 2001 and 2002 by neutron activation analysis)

22. Fibers & Textiles Used to create a link between crime and suspect
Locard’s Exchange Principle
Originate from carpets, clothing, linens, furniture, insulation, or rope
Direct transfer: suspect to victim or victim to suspect
Secondary transfer: victim picks up fibers from another source and then transfers to suspect (and vice versa)
Early collection is key!
Within 24 hours, 95% of all fibers may have fallen from a victim or been lost from a crime scene
The more unique the fiber, the more useful it is
Textile: most common form of fiber (clothing, carpets, upholstery)
Constructed by weaving yarns, which are made up of fibers that have been spun together

23. Gathering & Analyzing Fiber Evidence
Special vacuums, sticky tape, forceps
Accurate recording of location is essential to ensure evidence is admissible into court
Analyzing without damage
polarizing light microscopy – special filter that allows use of specific wavelengths of light
compound light microscope – natural fibers
infrared spectroscopy – emits a beam that bounces off the material and returns to the instrument
Reveals the chemical structure of the fiber, allows differentiation of similar fibers
Analyzing with damage
Fiber burn test or dissolving in various liquids

24. Natural Fibers Animal Fibers (made of proteins)
Hair: wool (sheep), cashmere (goats), mohair (goats), angora (rabbits), camel
Webbing: silk (cocoons of caterpillar Bombyx mori) – doesn’t shed as easily as hair
Fur: not a textile, sheds easily
Plant Fibers (specialized plant cells) – all have cellulose (carbohydrate)
Cotton (seed fiber)
Coir (fruit fiber – coconut) – used in doormats and baskets
Hemp, linen, jute, and flax (stem fibers)
Manila, sisal (leaf fibers) – often in ropes, twines, netting
Mineral fibers
Fiberglass, asbestos

25. Natural Fibers

26. Synthetic Fibers
Polymers – drained through spinnerets to make fibers that can be spun into yarns
Can be regenerated fibers (modified natural fibers) or synthetic polymers (petroleum – based)
Check your labels…what kinds of synthetic fibers do we have in here?
Rayon, Polyester, Nylon, acrylics, Acetate

27. Yarns & Textiles Spin short fibers to make yarns Textiles: woven yarns
Rope is a big yarn!
Direction of twist varies from yarn to yarn
Textiles: woven yarns
Different patterns of weave
Tabby – 1/1 weave
Twill – 3/1 weave (jeans)
Satin – 3/1, 4/1, 5/1, 6/1 or more
Thread count also differs (# of threads in a given amount of fabric)

28. Testing Methods Microscopic Examination Burn Testing Chemical Testing
Solubility
Dye
Chemical properties

30. Case Study Atlanta Child Murders - Wayne Williams
1980s, 11 month killing spree of African American youth in Atlanta’s poor neighborhoods (28 murders, two adults)
Victims were asphyxiated by rope or smothering and dumped in dumpsters or wooded areas
Police officers staked out a bridge over the Chattahoochee River and a white station wagon stopped, tossed something over the bridge, and drove off
Driver was 33-year-old Wayne Williams, arrested on suspicion of murder
Fibers matched the carpeting in his house, but no fibers from victims were found in his home other than a single red cotton fiber
Found guilty of two of the murders and sentenced to consecutive life sentences, still maintains his innocence