Prosecutors have always faced the struggle of finding enough evidence to convict defendants in criminal cases. Prior to the widespread use of DNA evidence, law enforcement agencies had to rely on various means of identifying defendants in cases of murder, sexual assault, and other crimes where the identity of the perpetrator was in question. One particular means of identification that was frequently used was microscopic hair analysis.
Microscopic hair analysis involves looking at pieces of hair through a microscope in an attempt to find a match to hair found at the scene of a crime. The FBI has used the practice for decades and has put on hundreds of training seminars for state examiners to train them in the procedure. The problem is that there are serious limits to the accuracy of the process. In many cases, examiners have not received proper training and have overstated the accuracy of their findings at trial.