How Do Scientists Use Hair in Crime Scene Investigations?

We’ve all watched television programs like “CSI: Crime Scene Investigation” and “Law and Order.” Shows like these simplify the investigative process that investigators conduct in trying to solve the mysteries behind crimes. If you’ve paid close attention, you may have noticed investigators collecting and examining hair as evidence in crime cases. How is the hair used to solve the crime? The study of the hair follicles found at the scene goes beyond the hair color.

Three layers of the hair shaft are used in determining how a crime was committed and who the criminal may be. The medulla, the innermost core of the hair, can be used to determine the race or ethnicity of the potential perpetrator.

The cortex is the layer over the medulla and is used to compare one hair to another. Microscopic air bubbles and pigment granules help scientists distinguish between the hair types. The outermost layer, the cuticle, can be used to determine the species (if the hair belongs to an animal) through analysis of the patterns of scales that cover the cortex.

In terms of investigation, the root of the hair can be one of the most useful pieces of evidence. By the root (or lack thereof), scientists can tell if the hair was shed naturally, pulled out, or cut off. The root is where investigators can find DNA to help precipitate their analysis. If a hair is pulled out during the anagen phase of the hair growth cycle a root bulb will appear with follicular tissue. This tissue has nuclear DNA which helps create a DNA profile unique to the hair’s owner.

During the catagen stage, the root of the hair pulls away from the shaft, and the hair is easily pulled from the head. The root bulb is less round and more elongated in this phase. In the final stage, the telogen phase, the hair sheds naturally and has a club-shaped root bulb. These two phases do not produce a follicular tag, which means nuclear DNA cannot be harvested from hairs in the catagen and telogen phases. However, mitochondrial DNA may be found in just the hair and can help to narrow down subjects, though it cannot distinguish between siblings.

Hair is also useful in chemical tests since it is often the only evidence still remaining after other bodily evidence has disappeared. Scientists can determine the presence of chemicals, poisons, heat treatments, and more. The important thing to note about the use of hair in investigations is that it is only one piece of an investigative puzzle. Hair cannot be used as evidence on its own. However, it can be very useful along with other pieces of evidence. Who knew your hair held so much information?

For more information on healthy hair, hair loss, or hair restoration, contact our office in Atlanta, GA. You can also find us on Facebook and Twitter with the latest in news, hair facts, and more!

Bertino, Anthony J., and Patricia Nolan. Bertino. Forensic Science: Fundamentals & Investigations. Mason, OH: South-Western Cengage Learning, 2009.

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Part 2 Causes of Hair-loss: Repeated Pulling Leading to Childrens Hair Loss

In our previous blog post detailing the causes of hair-loss we discussed the role of genetics and its contribution to the development of androgenetic alopecia and alopecia areata.  Often, for children who exhibit hair-loss, the causes might not be as simple as genetics.  For a small percentage of children ages 6-12 (mostly tween-age) a behavioral condition known as trichotillomania may be to blame for areas of hair-loss.
Most commonly referred to as “hair-pulling disorder,” or sometimes “trich,” this ailment is driven by a compulsion that causes children and adolescents to pull strands of hair from their scalp and occasionally their eyebrows and even body. The condition often begins with children wanting to continually twist their hair and place it in their mouth.  While the condition has been greatly dramatized for plot development on episodes of FX’s Nip Tuck and Showtime’s Nurse Jackie, if the neurosis continues, the child may begin to pluck the strands of hair and leave balding or stubbly areas of hair with differing thicknesses across the scalp.  This is different from the perfectly rounded, completely bald circles caused by the genetically linked alopecia areata.
Physicians see a majority of trich patients recover fully from the condition and re-grow their missing hair completely, with no need for medicine or surgery, by ceasing the pulling behavior. However, Dr. Edmond Griffin of The Griffin Center of Hair Restoration and Research warns that patients, especially children, must be properly diagnosed before any hair restoration treatment is approached.  It’s important to note that hair-restoration therapy to remedy the effects of this type of behavior are only viable options for patients who have completely stopped the repeated action of pulling for at least 1 year.
To learn more about stress related hair loss in men, women, or children and the non-surgical hair-restoration options contact our office, visit our website, or subscribe to our blog.

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