1. Warm-Up
Something extraordinary happened on May 6th 1978 at 12:34am, what was it that happened?

2. Hair Evidence

3. SKIN The skin has two layers:
Epidermis- this is the outer layer which is dead skin cells
Dermis- this is the living portion where hair is produced
Hair is composed of keratin, a type of protein

4. Function of Hair Regulate body temperature (insulation)
Decrease friction
Protect against sunlight
Sense organ

5. Hair Shaft Three layers: Cuticle: surface of hair
Cortex: main body, contains pigment
Medulla: hollow core

6. Hair Diagram

7. The Hair Growth Cycle Hair follicles grow in repeated cycles.
Anagen - Growth Phase
Approximately 85% of all hairs
Vary from two to six years.
Hair grows approximately 10cm per year.
Catagen - Transitional phase
Lasts about one or two weeks.
Hair follicle shrinks to about 1/6 of the normal length.
The lower part is destroyed and the hair may fall out.
Telogen - Resting Phase
Lasts about 5-6 weeks.
Approximately 10-15% of all hairs are in this phase at an one time.
At the end of the Telogen the hair follicle re-enters the Anagen phase.
Lower part reforms and a new hair begins.

8. Cuticle : Outer Layer Transparent, outer layer
Scales point down from younger end towards older ends of hair
Has three patterns
Coronal (crown-like)
Spinous (petal-like)
Imbricate (flattened)
Can have combinations

9. The coronal, or crown-like scale pattern is found in hairs of very fine diameter and resemble a stack of paper cups. Coronal scales are commonly found in the hairs of small rodents and bats but rarely in human hairs.

10. Spinous or petal-like scales are triangular in shape and protrude from the hair shaft. They are found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some other animals. They are never found in human hairs.

11. The imbricate or flattened scales type consists of overlapping scales with narrow margins. They are commonly found in human hairs and many animal hairs.
Photomicrograph of Human Hair Scale Pattern

12. Cortex: Color Layer Largest part of hair shaft
Melanin = pigment granules

13. Pigment granules are absent in grey hairs

14. Properties of the Medulla
Medullary index (ratio of medulla:shaft)
Pattern (continuous, interrupted, fragmented, or absent)
Shape (human vs. animal)

15. Human Medulla Patterns

16. Medulla Shape
In human hairs, the medulla is generally amorphous (without shape) in appearance.
In animal hairs, its structure is frequently very regular and well defined.

17. Animal

18. Human

19. Body Area Head (scalp) Eyebrows and eyelashes Beard and mustache
Underarm
Axillary (underarm) or body hair
Pubic hair
Pubic Hair
Beard Hair
Limb Hair

20. Mongoloid (Asian) Hair
Racial Origin
Negroid (African)
Mongoloid (Asian) Hair
Caucasiod (European)

21. Scissor-cut
Broken
Burned
Razor-cut

22. Dyed Hair
Lice Egg Case

23. DNA Evidence
Shaft: mitochondrial DNA (mtDNA)
Root: nuclear DNA

24. Collecting Hair Evidence
Methods used to collect hairs from clothing and bedding items are:
Scraping
Shaking
Taping
Picking
Debris from large carpeted surfaces might be vacuumed into a filtered canister.
If the specific location of a hair on a clothing item is important, it might be necessary to pick off the hair or tape the item and record where the hair was removed

25. Testing For Chemicals
Neutron activation analysis (NAA) – identify 14 different elements in hair
Antimony, argon, bromine, copper, gold, manganese, silver, sodium, zinc
Hair grows about 1.3 cm per month – calculate timeline for exposure to toxins or poison

26. Testing the Hair Follicle
Macroscopic views indicate length, color, and curliness.
Microscopic views indicate fine detail in hair structure.
The follicle can be blood tested or DNA analyzed.