How do forensic scientists compare class characteristics of evidence?

How do forensic scientists compare class characteristics of evidence?

If, for example, we're comparing hairs we will look at the length of the hair, the diameter of the hair, and the color of the hair. All of this would be done under the comparison microscope. It is the same with fibers - if we're comparing fibers we're going to look at the color, were going to look at the diameter, we are going to look at their morphological appearance under the microscope and we're also going to examine that fiber for its chemical identity. It really depends what we're looking at, and there are so many different items or potentially items with physical evidence that could be collected at a crime scene. Each one must be examined individually and by a specialist who must pick out two of the appropriate characteristics that will ultimately allow for a comparison.