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Forensic Science Hair Evidence: Animal vs. Human.

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Presentation on theme: "Forensic Science Hair Evidence: Animal vs. Human."— Presentation transcript:

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.  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  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

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

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 Do “Explore” Page 17


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