Forensic Hair Analysis

Hair evidence is one among the foremost common sorts of evidence encountered in criminal investigations. During the course of the normal hair-growth cycle, hairs are readily lost from individuals, and these hairs may be transferred during the course of a criminal activity. Edmond Locard was the first forensic scientist to formally articulate the foundation for the transfer event (Locard 1930). Now known colloquially as the Locard Exchange Principle, it states that any time there is contact between two surfaces, an exchange of materials will occur. One of the materials which will be readily collected, identified, and compared is hair evidence. The forensic analysis of hair evidence are often extremely valuable within the examination of physical evidence by (1) demonstrating that there may are an association between a suspect and a crime scene or a suspect and a victim or (2) demonstrating that no evidence exists for an association between a suspect and a crime scene or a suspect and a victim. Although the science of microscopic hair examination can never end in identification, that is, conclude that a hair came from one individual to the exclusion of all others; the vast amount of both macroscopic and microscopic information available from hair analysis can provide a robust basis for an association and positively provides strong exculpatory evidence.