The Forensic Identification and Association of Human Hair

Abstract

This chapter reviews pertinent concepts underlying the forensic examination of human hair and helps the reader understand, describe, and interpret particular data with respect to this forensic science. Human hair is particularly useful associative evidence because it originates directly from the individual. Since hair continually falls from the body of every person, it is often present at the crime scene or on the clothing of the participants. By the beginning of the twentieth century, the significance of hair in criminal investigations had come under scrutiny by a growing number of medicolegal experts. Forensic scientists in newly opened crime laboratories applied microscopy to the identification and association of hair and used it as evidence. A microscopical examination of a hair cross section reveals an outer layer of cuticular scales that surrounds the shaft, an inner darker portion called the cortex, and—in the center of the cortex—a canal-like structure called the medulla.