Hair and Fiber Analysis

The History of Hair/ Fiber Analysis


     The mere idea of the scientific study of hair, trichology, was published in France in 1857. This study rapidly grew in the early 20th century after the examination of microscopic hair. The basis for hair analysis information was published in 1937 written by Professor John Glaister titled "Hairs of Mammalia for the Medico-legal Aspect". The groundwork for the use of hair evidence was published in 1977 written by John Hick titled "Microscopy of Hairs: A Practical Guide and Manual". The use of forensic hair analysis has played a major role in courts. In one case a piece of hair helped a convicted man, James Driskell, who sat in prison for 12 years become innocent. 

Labeled Parts of a Complete Hair

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Wool

The Major Types of Fibers

Synthetic fiber

     Fibers have two categories, natural and synthetic. Natural fibers are hair-like materials that are similar to pieces of thread that are able to be spun into thread or rope. A few examples of natural fibers are wool, cotton and linen. Synthetic fibers are created by forcing fiber forming materials through holes to form a thread. A few examples of synthetic fibers are polyester, acetate and nylon.




Techniques for Collecting Hair/Fiber

     The collection of fibers at a crime scene are based on the fiber's size. For instance, if the fiber was large investigators would pick the fiber up with their fingers and then place it inside a small envelope. When smaller fibers are present investigators will wrap the area, in paper if possible, and send the evidence to the lab for analysis.

How do Scientists Analyze and Use Hair/ Fiber Data

A forensic scientist collecting hair/fiber evidence

     The analysis of hair samples determine whether its an animal or human. Examination of human hair can help scientists determine the race, body area, the removal of the hair, alteration (bleached or dyed) and the damage done to the hair. Keep in mind that the hair sample cannot actually identify a person, just their characteristics.  Fiber samples allow scientists to identify whether the sample is animal (wool), vegetable (cotton), mineral (glass), and synthetic (manufactured). Once identified the fiber can be compared to fibers from the victim, a suspect's clothing, a vehicle's interior, the fabric in a carpet, etc.  

How Reliable is Hair/ Fiber Data in Crime Scenes?

     Even though hair and fiber evidence cannot be used to narrow down one suspect, the evidence can be extremely helpful in closing in on a group of suspects. Following the proper procedure to collect the evidence is essential since failure could drastically lower the chances of obtaining a suspect. 

     Collecting the hair from the same area of the body is important since the physical characteristics of hair vary depending on the parts of the body. If a forensic scientist were to compare two types of hair found on the body a match would be improbable. Also, when obtaining hair evidence, it is vital to collect the entire length of hair because a piece of hair can show variation in color or other physical characteristics. Head hair usually contains about 50 full-length hairs, which is approximately 24 full-length pubic hairs for a qualified sample. The length of hair below this will become very difficult or impossible to form connections with a suspect.

     Collecting fiber evidence can prove to be difficult since fibers commonly can’t be seen by the naked eye. Any piece of material that contains relevant fibers should be bagged separately in preferably paper bags. The preservation of any fibers is stressed by forensics because contamination is very probable. Contaminated fibers dramatically decrease the chances of finding critical evidence that may have been needed to solve a case.

 Famous Case

                    

    A serial killer named Ted Bundy was responsible for an estimated 30-plus deaths, but with a lack of physical evidence to link him to the claims when he was arrested in 1975. Two years later Bundy was accused of kidnapping and was prepared to stand trial for murder in Colorado. Unfortunately he escaped and headed to Florida where he killed 3 more people in early 1978. He was captured in February during the same year due to the physical evidence. The most evident evidence was the bite mark left on the butt of Lisa Levy which was matched with Bundy’s distinctive, crooked and chipped teeth. With conviction of another murder, 12-year-old Kimberly Leach, fibers were found in Bundy’s van that matched the young girl’s clothing. Ted Bundy was put to death in 1989. 

Hair/ Fiber Lab

     In this lab my group and I were given 10 hair/ fiber samples and was told to observe these samples beneath a microscope and record the samples' color, condition of the tip, any observable distinguishing features, and a drawing was required. While observing the samples we noticed that some of the darker haired samples seemed to have a violent tint to them. This was the result of rays of sunlight reflecting off the hair.