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Aim: How is hair analyzed in forensics?

Aim: How is hair analyzed in forensics?. Homework: Pg. 230 #’s q 1-10. Do Now: Explain the possible drawbacks of analysis of hair for drug metabolites. What other materials can be traced in hair?. Poisoning by heavy metals (Arsenic, Mercury, lead)

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Aim: How is hair analyzed in forensics?

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  1. Aim: How is hair analyzed in forensics? Homework: Pg. 230 #’s q 1-10 Do Now: Explain the possible drawbacks of analysis of hair for drug metabolites.

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

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

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

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

  6. 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

  7. 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

  8. Wednesday 4/18/12 • AIM: how can we determine the ethnicity of a hair sample? • DO NOW: Explain how you would determine the species of a hair sample? • HOMEWORK: textbook page 230-231. questions 11-15. • I AM COLLECTING MONDAY TUESDAY AND WEDNESDAY’s Homework TOMORROW

  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. Thursday 4/19/12 • AIM: How can we determine the origin of a hair sample? • DO NOW: 1- Take out the homework from Monday, Tuesday and Wednesday • 2- 2 minute mystery: speeding train • Homework: THERE IS NONE!

  13. How can you determine the part of the body a hair comes from?

  14. SCALP HAIR: small variation in diameter uniform distribution of pigment color Can The Body Area From Which A Hair Originated Be Determined? PUBIC HAIRshort and curly wide variation in diameter. BEARD HAIRcoarse, triangular in cross section blunt tips from cutting or shaving.

  15. 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)

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  21. Hair analysis video

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