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Forensic Science

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

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Forensic Science

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  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 person’s 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 Hair:Color • 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 Hair:Tip • 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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