There are many types of trace evidence that crime scene investigators and forensic scientists can use to find and convict suspects. One of these is fiber evidence analysis. Some of you may remember the trial of serial killer Wayne Williams, but you may not recall that part of his conviction revolved around fiber traces. The only real clue in the Atlanta killings was the presence of fiber threads on several of the bodies and their clothing. The Crime Library site details the investigation in which yellow-green carpet fibers were found on some of the bodies, which ultimately tied into carpeting found in Williams' home. Even though other people had the same type of carpeting which had only been made during the span of one year by a Boston-based company, the FBI determined only eighty-two homes in Georgia were carpeted with Luxaire English Olive. In addition, a single rayon fiber had been found on shorts of one of the victims, which was consistent with the carpeting in Williams' station wagon.
In another case, which this Connecticut Department of Safety site details, a carpet installer was accused of sexually assaulting two girls. Comparison microscopy helped determine that the same olefin fibers found on the girls' clothing were also found on the clothing of the suspect and in his van.
For a detailed look at fiber (and hair) trace evidence, you can check out the following FBI Site.