What Information Can a Forensic Scientist Determine From a Human Hair?

Presence of Poison

When forensic scientists analyze the hair of a crime victim, they can determine if poison—such as arsenic—was involved in the case. This is because hair is absorbent and can pick up any poisons that are present inside of someone’s bloodstream. By examining a victim’s hair, it is possible to determine how much poison is in the victim’s system and how often the poison had been administered.

Although forensic scientists cannot determine someone’s exact age from analyzing hair, the hair can give some clues about someone’s approximate age group. The hairs from an infant, for example, will appear finer and less distinct when examined under a microscope than adult hairs. Also, hairs that have lost their pigment may be an indicator that they came from an older person.

When forensic scientists examine hair under a microscope, they are not able to determine what someone’s gender is. However, visual inspection may yield important clues if the hair has been treated, as that is generally associated with women more than with men. If the hair being examined still has its follicle, forensic scientists can get some insight about gender by running tests on the follicle, however, it is more common to run DNA tests on hair to find out gender information.

In many cases, someone’s race can be determined when forensic scientists examine a hair under a microscope—although if the hair came from an infant, or if the hair contains unusual racial characteristics, this may not be possible. Generally there are three types of hairs that forensic scientists examine: Caucasoid (coming from people of European descent), Negroid (coming from people of African descent), and Mongoloid (coming from people of Asian descent).

When forensic scientists examine hairs, they can often determine some details about how a crime was committed. Forensic scientists look at hairs to see if they were forcibly removed or if they shed naturally from someone’s body. If a hair was pulled from someone’s body, it can be indicative of a violent struggle that occurred during the course of a crime.