Although not considered "trace" items by definition the many Crime Labs also examine and analyze such important evidence as flammables (in arson investigations), fingerprints, footwear (shoeprints), and "fracture matches." Many also perform examinations of automobile headlamps, taillights and speedometers. .
The first category of trace evidence I will discuss is hair. Hair is examined grossly (with the naked eye), and with both low power and high power microscopes to determine if questioned hairs, found at the scene or on the clothing of an individual are consistent in characteristics to known hair collected from the suspect and/or victim. Some of these characteristics include more obvious traits such as color, length, and morphological shape and also microscopic aspects of the cuticle, cortex and medulla, which are the three basic components of a hair. A hair cannot be linked specifically to an individual through these methods but vital information developed as to who the suspect may be and significant elimination of other suspects can often be done. It is possible to tell the race, sex, and region of the body that a hair comes from. A relative .
idea as to the time since the last haircut can also be made. .
The second type of trace evidence is glass. When larger samples are available glass can be useful in linking a suspect with the crime scene through "fracture matches". This is when a larger piece of glass, found associated with the suspect, can be physically fitted with one or more pieces from the crime scene. More often when an individual gains access to a business or dwelling by breaking glass the perpetrator will acquire very tiny pieces of glass on his/her clothing. These cannot be physically matched due to their tiny size. However, these pieces, though smaller than a pinhead, can be characterized under the microscope. .
After proper gross and low power microscopic examinations are performed the Forensic Scientists use microscopic "refractive index" determination to further characterize the samples.