Analyzing Hairs Forensic Science.

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Presentation transcript:

Analyzing Hairs Forensic Science

Morphology of Hair Hair grows out of a hair follicle Shaft: the length of hair that is found above the skin Shaft is composed of three layers: Cuticle, Cortex and Medulla

Cuticle Scaly structure that covers the exterior of the hair Scales always point to the tip of the hair Pattern can be used to identify species Helps to make the hair resistant to chemical decomposition and to retain its structural features

Cortex Main body of the hair shaft Made up of spindle-shaped cells that are aligned parallel to the length of the hair Pigment granules are found in the cortex Important points of comparison are provided by the color, shape and distribution of the pigment granules

Pigment granules found in cortex of hair

Medulla Collection of cells composing the inner canal of the hair In animals, the medulla is the biggest feature Medulla can vary within the individual Three main medulla patterns: Continuous, Interrupted and Fragmented

Medulla Patterns

Root Helps to produce hair and continue growth Shape and size can determine the growth phase of the hair

Phases of Growth Anagen Phase: Initial phase of growth when the follicle is producing hair Catagen Phase: Transition phase between anagen and telogen Telogen Phase: Final phase where the hair naturally falls out

Pictures of Phase of Growth

What can be determined from hair? Racial Origin Male or female if tissue adheres to the hair Whether the hair fell out or was forcibly removed Type of hair (what part of body it originated in)

Collection and Preservation Must collect reference/standard samples from SAME part of body where the hair originated 25-50 full length hairs collected for reference sample Hair can be pulled or clipped at skin level