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April 30, 2013 Positive Attitude Peccadillo: a slight offense or fault; a minor sin Do Now:

April 30, 2013 Positive Attitude Peccadillo: a slight offense or fault; a minor sin Do Now: What is hair? What can be learned through forensic analysis of hair?. Why study hair?. Hair is a record of recent activities. Hair is a record of life exposure to nutrients.

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April 30, 2013 Positive Attitude Peccadillo: a slight offense or fault; a minor sin Do Now:

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  1. April 30, 2013 Positive Attitude Peccadillo: a slight offense or fault; a minor sin Do Now: What is hair? What can be learned through forensic analysis of hair?

  2. Why study hair? • Hair is a record of recent activities. • Hair is a record of life exposure to nutrients. • Hair is a record of chemicals / radiation.

  3. What other materials can be traced in hair? Poisoning by heavy metals (Arsenic, Mercury, lead) Dietary deficiencies (low vitamin and mineral levels)

  4. What is a drawback to hair testing? Scalp oils coat the cuticle of the hair and sometimes capture materials from environment Ex: smoke Can cause “false positives” Scientists must be careful to examine only the cortex of the hair

  5. Types of Animal Hairs - Key Cat Rabbit Rat A B C Human Dog D E

  6. Parts of a hair strand • 3. Tip/ End of Hair • Often seen burned cut, razored, or with split ends

  7. How do we get different hair colors? 1. The type of natural color pigment melanin present in your hair's cortex. • Eumelanin (black pigment) • Phenomelanin (red/yellow pigment) 2. How many melanin granules exist 3. Whether those granules are close together or far apart

  8. How do we get straight, wavy, curly, and kinky scalp hair? -It is due to differences in the cross section of the hair Typically found in people of Native American and Asian descent Typically found in people of European descent Typically found in people of African American descent

  9. How does scalp hair vary by race? • Asian/Native American • Round hair shaft - straight • Large pigment granules • Patchy distribution of pigment • Usually continuous medulla • European/Caucasian • Slightly round to oval hair shaft (straight to curly) • Finer pigment granules • More even distribution of pigment • Usually absent or fragmented medulla

  10. How does scalp hair vary by race? • African American • Flat to oval hair shaft (curly to kinky) • Largest and most dense pigment granules that are unevenly distributed -Absent or fragmented medulla

  11. HEAD HAIR: Caucasian (left) Asian/Native American ( bottom left) African American (bottom right)

  12. Can the Age & Sex of an Individual Be Determined from a Hair Sample? SEX - can be determined if DNA is found on the hair. AGE - cannot be determined from a hair examination with certainty. (except an infant)

  13. Is It Possible to Determine If Hair Was Forcibly Removed from the Body? Hair naturally falling off the body will show a root without any follicular tissue. A hair root with follicular tissue means that the hair had been pulled out either by another person or by brushing.

  14. How Can We Individualize Human Hair? DNA from the follicular tag can be matched to one individual This is the best source of DNA in hair. FOLLICULAR TAG – a translucent piece of tissue surrounding the hair’s shaft near the root.

  15. Collection & Preservation of Hair Evidence 50 full-length hairs from all areas of the scalp may be collected as samples Use a piece of tape to collect and package hair samples from a crime scene Hairs found at the crime scene are compared to samples from the victim and from the suspects

  16. What causes gray hair? • As you age, the natural production of pigment slows down and your natural color loses its color strength. • Doesn't happen to every hair at the same time, so the contrast between the hair with no color and the hair that still has some color causes it to look gray. • So how gray your hair actually looks is determined by the percentage of strands with no color vs. the pigmented strands.

  17. Root of Hair • Provide the tools to produce hair and continue its growth • 3 Stages of Growth (different looking roots) • Anagen -initial phase may last up to 6 years, root is flame shaped • Catagen –transition phase (2-3 weeks), root is elongated • Telogen –phase where hair naturally falls out of the skin, root is club-shaped

  18. Hair analysis video

  19. Total Magnification • Ocular x objective = total magnification Ex: 10 x 10 = 100 magnification 20 x 40 = ? It is very important to note the ocular magnification.

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