Most trace evidence found at a crime undergoes forensic analysis for two main
purposes: identification and comparison. Often tiny strange particles are found, and testing for
identification purposes establishes exactly what the material is. Obviously, this is a vital step in
determining if questionable substances left at a crime scene are traces of blood, illegal drugs, or
if hairs collected are human or animal. Comparisons attempt to determine if the evidence found
at a scene shares a common origin with that from a suspect. For example, crime-scene fibers
would be compared with fibers from clothing, carpets, etc. of a suspect, to see if they match.
The primary significance and most valuable characteristic of trace evidence is it can
unknowingly be transferred from one person to another, or between a person and crime scene.
During the commission of a crime, tiny particles of items such as hair, fibers, dirt, blood, skin or
saliva from a perpetrator are transferred to clothing, hair, etc. of a victim, or vice-versa. This
evidence is vital, as often it is the only thing that connects suspect to the crime scene and was
first brought to the attention of investigators in the early 1900s, by Edmond Locard, a French
police officer. This is the real cornerstone of forensics and known as Locard’s Exchange
Principle. (Lyle, 2004).
Two types of trace evidence often recovered at crime scenes are hair and fibers. While
in most cases, evidence of this nature cannot conclusively identify a particular person, it is a
valuable source of associative evidence.
Analyzing hair evidence
Prior to the year 1900, scientists could not differentiate human hair from animal hair, as
no information on the subject was available. Failure in this area meant hair had little value as
forensic evidence; therefore, an ineffective support for investigators.
Francois Goron, Chief
Hair and Fiber