Hair and Fibers

Hair and Fibers in an Investigation

  Hair and fibers found on the scene or in relation to a suspect can link them to a crime scene or a victim using their hair, clothing or even their vehicle to provide evidence. Hair can provide race, sex and offer the possibility of DNA extraction.

  Fibers are viewed under a microscope in order to identify or match the fiber to another. Hair is also examined under a microscope in order to establish the ethnicityand gender of the owner of the hair by looking at the patterns and markers on the hair.

Hair and Fibers in Court

 Hair and Fiber evidence holds up well in court on the side of the prosecution, when proving a suspect was at the scene of the crime, but just because hair and fibers found don’t match a suspect, it doesn’t mean the suspect wasn’t there. For this reason, Hair and Fiber usually works best as supporting evidence, with more definite evidence as the main case-builder.

 Also for that reason, Hair and Fiber evidence is more likely to condemn a suspect than exonerate a suspect. More cases have been seen where the suspect is convicted on fibers than an old cases reopened frees a suspect.

 An example of a court case is the wildly publicized Jeffery MacDonald case. A military doctor was convicted of killing his wife and two daughters after fiber evidence discredited his story of the supposed break-in and murder of his family. The verdict of the case is still disputed due in part to the fact that fiber evidence was the main condemning factor

Anatomy of a Hair

Human hair is distinctive under a microscope because of its “railroad track” pattern, with two lines of the same color on the outer edges and lines of a different color, usually lighter, between the “railroad tracks.” The tip can be cut or frayed, and hairs will often show a sort of scaling pattern along the shaft. Hair structure also differs between races. Here are some examples.

Asian Hair

Caucasian Hair

 African-American Hair

Other Fibers

Hair isn’t the only fiber found at crime scenes. Fibers come from clothes, carpets, cars and many other locations, so investigators need to be prepared to identify them.

Collecting Fibers

 When collecting evidence from a crime scene, investigators must be sure not to leave any fibers of their own by using protective clothing when on the scene. Once this is achieved, fibers can be collected with sticky tape, forceps and a variety of other tools then places in test tubes or evidence bags for transportation to a lab.

History of Hair and Fiber Analysis

 Hair and fiber analysis are somewhat new to the investigative world, dating back less than 40 years. This is due to a combination of the fact that such small fibers weren’t looked at nor were they able to be looked at so closely until relatively recently.