Cycle, Medullary Index, CSI
Hair consists of a protein call keratin. This same protein is found in your skin and nails.
Hair consists of three layers: Inner- only found in thick hair Middle- known as the cortex and provides the color and texture Outer- known as the cuticle and is the protector
This is the diameter of the shaft and helps tell the difference between animal and human hair.
Hair as Evidence
If the root is attached hair then holds DNA and a suspect can be narrowed down. If there is no root the hair can then be examined under a microscope and compared to that of suspect's.