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Forensic Science

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Forensic Science Hair Evidence: Animal vs. Human * * Hair Evidence Many class characteristics can be determined; these characteristics can be used to eliminate suspects. – PowerPoint PPT presentation

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Title: Forensic Science


1
Forensic Science
  • Hair Evidence Animal vs. Human

2
Hair Evidence
  • Many class characteristics can be determined
    these characteristics can be used to eliminate
    suspects.
  • Forensic scientists can determine whether the
    hair was forcibly removed, damaged by burning, or
    artificially treated by dyeing or bleaching.
  • The region of the body where a hair originated
    can be determined with considerable accuracy by
    its macroscopic and microscopic characteristics.
  • In certain instances, a persons race can be
    deduced from the hair.

3
Types of Human Hair
  • Head hair
  • Pubic hair
  • Underarm hair
  • Beard/mustache hair
  • Eyebrow/eyelash
  • General body hair

Certain features of individual hairs identify the
region of the body where it originated.
4
Where is this Hair from?
5
Where is this hair from?
6
Where is this hair from?
7
What is this?
8
  • Head hairs and pubic hairs exhibit a greater
    range of microscopic characteristics than other
    human hairs
  • therefore, head and pubic hairs are routinely
    forensically compared.

9
Hair Characteristics Race
  • Human hairs can be classified by racial origin
    such as
  • Caucasian (European origin)
  • African-American (African origin)
  • Mongoloid (Asian origin).
  • In some instances, the racial characteristics
    exhibited are not clearly defined, indicating the
    hair may be of mixed-racial origin.
  • Racial indicators apply primarily to head hairs.

10
  • Caucasian
  • African-American
  • Mongoloid

11
Human vs. Animal Hair
  • How do you tell the difference?

12
Animal vs. Human HairColor
  • Human hairs are generally consistent in color and
    pigmentation throughout the length of the hair
    shaft, whereas animal hairs may exhibit radical
    color changes in a short distance, called
    banding.

13
Human vs. Animal Hair Medullary Index
  • The medulla, when present in human hairs, is
    generally less than one-third the overall
    diameter of the hair shaft. (MI ??)
  • The medulla in animal hairs is normally
    continuous or interrupted, and it generally
    occupies an area of greater than one-half the
    overall diameter of the hair shaft. (MI ??)

14
Human vs. Animal Hair Cuticle
  • Human hair is imbricate (flattened)
  • Animal hair varies by species, but can be
    spinuous or coronal, as well as imbricate

15
Human vs. Animal HairTip
  • Scissor cut or razor cut implies the hair has
    been groomed. Many animals are not groomed so
    if you see a scissor cut tip or a razor cut tip
    it might be a clue that the type of hair you are
    looking at did not come from an animal.

16
  • Do Explore
  • Page 17
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