Our bodies lose hair daily. In fact, we shed hair from various parts of our body and in most cases are simply unaware of the occurrence. On many occasions, I have collected hair as evidence at crime scenes. What types of information can be gleaned from hair?




Hair can be an important item of trace evidence. The shaft of a hair can reveal the type of animal it came from as all animals generate specific types of hair, while also providing identifiable characteristics on a class level. For example, a hair shaft contains Mitochondrial DNA, or mtDNA. This type of DNA is passed down through the maternal line, provided by the great grandmother, grandmother, and mother of a person. This DNA is often used to identify victims of crime by connecting the victim to siblings, mother, and grandmother; it cannot identify a specific individual. mtDNA is DNA located outside of the cell nucleus, and is the power source for the nucleus; it is found in much larger quantities than nuclear DNA. 

Nuclear DNA is found inside of the cell nucleus, it is the DNA passed down to each person by their mother and father, it is commonly found in the root of the hair. Hair roots are often attached to hair evidence that was forcefully removed from the body; this type of DNA can be used to identify a specific person as we all possess our own DNA profiles. The only exception to this is with identical twins. Hair analysts can not only identify if a hair came from a mouse, cat, dog, or human, but also the type of dog. 

Hair can be a key item of evidence. However, it can also be misleading due to its ease of transfer from one location to another. For example, someone sharing a cab ride with other citizens can pick up a hair sample from the cab seat days before losing that sample in a crime scene. Hair evidence can be transferred on coats, hats, scarves, and footwear. This evidence simply presents investigators with leads to use in the course of their investigations. A hair present within a crime scene does not necessarily mean the donor was at the scene, this is part of the "context" of the evidence and scene that investigators need to piece together. 

Hair can also be used to detect traces of drugs and poisons. On more than one occasion, I collected hair samples from children who had been exposed to illicit drugs. The hair samples can be tested to determine the type of drug or poison within the body, and also the time period the drugs or poisons were introduced to the body. The longer the strands, the longer the time period of measurement; analysts generally only need about a pencil's diameter of hair for testing. Hair evidence is normally located through an examination by the unaided eye, and the use of alternate light sources. 



Comments

Post a Comment

Popular posts from this blog

Image
Forensic Knowledge Test: What do the terms Cause, Manner, and Mechanism of Death mean? Also, by what means can investigators and medical examiners determine the Postmortem Interval (PI), or the approximate time of death of a victim? (Mount Wachusett Community College, 2022) Following the death of an individual, medical examiners and investigators must determine the cause, manner, and mechanism of death. The process is conducted to provide a final determination on the case and to allow investigators to close the case, or continue the investigation.  When we refer to cause of death , we are referring to the reason the person died. Disease, physical injuries, a stroke, poisoning, and a heart attack can all be considered causes of death.  Manner of death refers to the ways in which a person can die, and there are four manners of death. These manners are (1) natural death, (2) accidental death, (3) suicidal death, and (4) homicidal death. Undetermined can also be used if a medical...
Read more

Feces, DNA, and Identifying Perpetrators of Crimes

Image
Deoxyribonucleic Acid or DNA can be found in many types of biological forms of evidence. From saliva, to blood, semen, urine, and sweat, DNA profiles can be developed, connecting perpetrators of crimes to crime scenes and crime victims. In Lakeville, Indiana, three construction workers were murdered at a construction site. Police had little to work with and no leads in the case. However, one investigator observed someone on the property recently stepped in a pile of dog feces. The footwear left a clear impression in the feces. It was determined that the footwear that made the impression was not from anyone residing on the property or the construction workers. The impression was captured through photography, and a sample of the feces was collected. With no leads, days passed until a call came in from someone advising they believed they knew who was responsible for the killings. With a possible suspect identified, investigators obtained a search warrant for the apartment where the ...
Read more
Image
Forensic Entomology and the Death Scene The dead can no longer speak for themselves. It is the job of the crime scene investigator to identify, document, collect, and preserve evidence of crimes that speak for the crime victim. In many cases, nature provides that evidence for investigators. Upon death, the body of the deceased immediately experiences physiological changes and begins the decomposition process. As the body decomposes, a common and predictable sequence of insects inhabit the body; this process is known as insect succession. Insects such as flies, wasps, beetles, and ants quickly attack the body if the deceased is not in a secure environment. Forensic entomologists identify insects from the crime scene, using accumulated degree hours (ADH) to estimate an approximate time of death. The ADH information allows forensic entomologists to estimate the time involved in developing the current stages of insect succession, in accordance with local conditions. It is the predictable p...
Read more