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Hair

Hair. …and more hair. Hair as Evidence. Can only compare head hair to head hair or pubic hair to another pubic hair Control hairs from suspect: 50 full length head hairs minimum of 24 pubic hairs. HAIR is useful as forensic evidence because its protein polymers are….

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Hair

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  1. Hair

  2. …and more hair.

  3. Hair as Evidence Can only compare head hair to head hair or pubic hair to another pubic hair Control hairs from suspect: 50 full length head hairs minimum of 24 pubic hairs

  4. HAIR is useful as forensic evidence because its protein polymers are… Resistant to decomposition and maintains its structure.

  5. The average human body has about 5 million hairs!

  6. Some HAIRY facts… The average number of Brown/Black scalp hairs: 100,000!

  7. On the average, the human scalp has 100,000 hair follicles. You are born with as many hair follicles as you are ever going to have!

  8. Blondes have 120,000

  9. Redheads have at least80,000

  10. Average daily # of hairs shed: 50 - 100

  11. Fastest Growth.. Between 15 and 30 years of age

  12. Slow Growth..

  13. Average Scalp hair growth… 0.35 mm/day or about 1 cm/month

  14. Hair grows faster … In summer

  15. Month of greatest hair shed in Northern Temperate zone: NOVEMBER

  16. Hair Morphology (structure)

  17. Sticks out of skin Structure from which hair grows Lies below epidermis Can differentiate Between species

  18. The organ that hair grows out of

  19. Cross Section of hairThe Hair shaft is made up of…. 1. The CUTICLE is the outside covering

  20. a. SCALES cover the cuticle The cuticle protects the cortex

  21. In Humans Scale patterns are not useful forensically because the scale patterns in humans are the same

  22. In animals, a variety of scale patterns are found deer bat mink

  23. Scales always point toward the tip of hair (1) mosaic

  24. (2) pectinate

  25. (3) imbricate

  26. (4) petal

  27. (5) Diamond petal

  28. (6) chevron

  29. 2. Cortex – gives hair its shape The bulk of each hair’s mass is contained in the cortex.

  30. The CORTEX… contains the various proteins and bonds which determine the curliness or straightness of the hair.

  31. a. melanin • Pigment granules that give hair its color

  32. b. Cortical fusi Air spaces Usually found near the root But can be found Throughout the Hair shaft

  33. 3. Medulla – “central canal” -Formed by cells running through hair -Amorphous in appearance

  34. Medullary Index = diameter of medulla diameter of hair This hair is .030 mm in diameter The medulla is approximately .005 mm In width The Medullary Index = .005 mm .030 mm = 1/6

  35. Degree of variations in medullas • Vary from one individual to another • And even between hairs of one person Human hair Medulla index < 1/3 in other animals: ½ or greater

  36. a. Types of medullas (Human) Interrupted or intermittent continuous absent fragmented

  37. b. Patterns (other animals) • Uniserial • multiserial

  38. (3) Vacuolated Mountain lion

  39. (4) lattice

  40. (5) Amorphous – without a clear form

  41. Hair as Evidence Determine… 1. Human or animal? In Humans: Medullary Index < 1/3 In Other Animals: Medullary Index ≥ 1/2

  42. 2. Race (ethnicity) Negroid hairs Negroid or African origin hairs are usually curly with a flattened cross section and appear to be curly, wavy, or coiled.

  43. Caucasian hairs Caucasoid or Caucasian origin hairs are normally fine to medium coarseness, oval cross-section, straight or wavy in appearance, and colors range from blonde to brown to black.

  44. Mongoloid or Asian hairs Mongoloid or Asian origin hairs are normally coarse, straight, with a wider diameter than hairs of the Caucasoid and Negroid hairs. The outer layer of the hair is usually much thicker than that of the other racial groups.

  45. 3. Origin –from which part of body • Scalp hairs - all about the same diameter • Beard hairs - coarse, blunt tips • Pubic hairs - short, curly

  46. 4. Manner in which hair was removed Forcibly removed hair will include the root tip

  47. Follicular Tag contains tissue surrounding hair shaft Contains DNA!!

  48. 5. Treated Hair a. roots

  49. b.Dye present in cuticle or cortex

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