Presentation on theme: "Hair Evidence: Animal vs. Human"— Presentation transcript:
1 Hair Evidence: Animal vs. Human Forensic ScienceHair Evidence: Animal vs. Human
2 Hair EvidenceMany 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 hairUnderarm hairBeard/mustache hairEyebrow/eyelashGeneral body hairCertain features of individual hairs identify the region of the body where it originated.
8 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.
11 How do you tell the difference? Human vs. Animal HairHow 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.