16 . December . 2019 BY Dr. Sharmishtha Deshpande

Ever heard about hair analysis assisting in solving a crime case? Wondering how hair and courtrooms are related? Well, yes. Hair can play a vital role in courtrooms!

Hair samples are one of the most important resources when it comes to the forensic analysis of a crime scene. It often provides valuable information that can help identify a suspect or victim, and add valuable inputs to deductions of the overall scene.

Forensic science, as Wiki says, is the application of science to criminal and civil laws. Its application is more important during criminal investigations. It involves collecting, preserving and performing analysis on various objects or evidence during the course of any investigation.

Our hair possesses different microscopic characteristics that help analyse an individual’s race, gender, colour and root appearance. Some eternal characteristics of the hair such as characteristics of colour, shape, texture and length can really help pin down facts in an investigation.

Why hair analysis for forensic study?

Hair analysis is extremely important in the field of forensic science, as it can answer questions that no other evidence may be able to. Supposing a person has been poisoned, traces of the poison can be found through hair analysis, studying hair samples long after the poison has left the body. A regular blood test may not show these traces after a certain point of time, but hair can reveal it! For this reason, the forensic application of hair analysis is also used in post-mortem investigations to clarify the cause of death, and understand drug-facilitated crime or assaults, etc.

Hair analysis is widely used as a tool for locating and eliminating suspects in crimes. Investigators are usually responsible for collecting hair samples from the crime scenes so that they can be analyzed later, to serve as crucial evidence and help put pieces of the puzzle together.

Importance of hair samples for analysis

Hair sample alone cannot help solve a crime. But it often provides sufficient inputs to help strengthen a case. As mentioned above, they can help in the deduction process, by giving some very basic information about the nature of hair colour, a specific race, whether the hair is coloured or not etc. It helps the investigators establish the presence or absence of a candidate and also perhaps draw conclusions about the basic features of a suspect.

As you know, hair is a protein that grows out of hair follicles. Every hair goes through a hair growth cycle – hair grows in the hair follicle, then stops growing, and eventually falls out when pushed by the new hair growing out. The hair sample collected is studied keeping these considerations in mind. The continual growth and replacement of human hair involve complex cellular transformation and regeneration events.

Hair samples collected along with the hair follicles intact are essential for DNA testing. Almost every cell type in the human body is nucleated and made up of chromosomes. These chromosomes are majorly made up of nuclear DNA classified as mitochondrial DNA.

Hair samples, especially from the growing phase (called the Anagen) contain large amounts of nucleated cells in the root and surrounding sheath material. However, most commonly encountered hair samples are from the falling phase called the Telogen. As a result, follicular tissue of them may not be suitable for general DNA analysis as they lack nucleated cells. However, they may contain sufficient amounts of mitochondrial DNA (mtDNA) in their roots and hair shafts for analysis.

Analysis mtDNA sequence from human hair has proven to be a valuable complement to traditional hair comparison microscopy in forensic cases when nuclear DNA typing is not possible. Thus, advancements in technology and application of new methods have broadened the horizon for DNA identification from the hair shafts.

A hair sample may not show the absolute recent changes in the body, like a drug consumed the same day, but hair analysis can definitely reveal drug use or exposure to chemicals over a few months time. Hair samples that are taken close to the root can show what drugs were used up to 3 months before the test. Hair analysis process is taken up as per the nature of samples available and the deductions are made accordingly.

Sounds complicated? It’s indeed a complex study that is carried out by highly trained professionals!

Also…while we are on the topic, you may also ask, why hair samples only from the scalp and not the rest of the body?

Yes, hair evidence can come from all over someone’s body, but the fact is, some hairs are more useful than others. Hairs from the face, chest and underarm are usually not tested by forensic scientists. As hair from the head and genital area have a unique nature, it yields more evidence and thus, can give a more accurate result while performing tests. Hair strands from a suspect’s head are plucked directly from different areas of the person’s head as well as taken from a comb along with samples found at any crime scene.

Let us now briefly touch upon how all of the above is put to practical use!

How is Hair analysis put to use in forensic studies?

Hair is one of the prima-facie diagnostic tools used when the possible cause of death is to be ascertained, in unusual or unforeseen circumstances. Unexpectedly, hair comes to your rescue. It helps in identifying the victim, finding out the sex of the person, his or her age, race, and genetic traits, also in the identification of the suspected assailant, especially in cases of sexual assault.

Not just that, hair also comes into the picture when the weapon used in a crime is to be identified. The forensic experts come to a conclusion as regards the instruments used in the crime by assessing the way the hair is cut/crushed, so on and so forth.

Experts can make keen observations, paying attention to absolute detail, minutely and precisely, to determine poison or chemicals used, gauge the time of exposure by doing certain chemical analysis, type of poison traceable in the hair, the time of the crime, whether hair is pulled out by force or it has fallen by itself etc.

Hair helps in forensic examination in the following ways:

  1. Victim identification
        Gender identification – Sex is determined by the appearance and distribution of the chest hair, beard and moustache and by detection of sex chromatin and Y-chromosome in cells of the hair root.
        Estimation of age – Age is estimated by the length, colour and location of hair. For instance, length of the scalp hair in a full-term infant is about 3cm; growth of the pubic, axillary (underarm) hair occurs at puberty; greying of hair typically occurs after a minimum of 30 years…
        Recognition of race – Texture, colour and arrangement of hair differ from one race to the other. Experts in the field are able to deduce the race depending on set established benchmarks that are largely proven and authentic.
      Genetic traits – Examination of genetic markers is possible from nucleated cells in the root sheath, as discussed earlier in this page.
  2. Identification of suspected assailant – This is done by comparing the hair present at the scene of the crime or in the hand of the victim with the hair of the suspected assailant. In some sexual assault cases, it has been observed that the assailant has some hair residue on his own body, that actually belongs to the victim.
  3. Identification of the weapon used in crime – This can be determined in the following ways:
    • By observing the manner in which hair is cut or crushed.
    • By comparing the hair present on a particular instrument with the victim’s hair.
    • By examining a particular vehicle for the victim’s hair in the case of hit-and-run accidents.
  4. In determining whether a particular wound is an incised wound or a contused wound depending on whether the hair is sharply cut or crushed.
  5. In determining the type of burn suffered by the victim: dry burns (singed hair with clubbing), scalds (wet hair) and corrosive burns (wet and eaten-up hair).
  6. In analysing injuries caused by firearms and estimating the distance of firing on the basis of singed hair and powder marks.
  7. In determining poisoning and its chronicity by checking for the presence of chemicals in the hair. Just as in case of heavy metals, poisons are deposited in the hair, starting from the root and extending to the tip. Chemical analysis of the hair helps not only in identifying the type of poison but also in estimating the time of exposure on the basis of the fact that hair fibres grow 0.4mm each day.
  8. In determining the time of crime by examination of the hair tip. The angle is acute when hair is recently cut, the end rounded after a few days and the end tapering after two weeks.
  9. In determining whether hair has been pulled out by force. Hair that has fallen by itself will have a degenerated root and hair that has been pulled out by force will have a healthy root with a ruptured sheath.

Apart from the above, recent advancements in the field are the hair follicle study for drug testing and HTMA.

Hair follicle drug test is used to determine patterns of illicit drug use or misuse of prescription medication over a period of time — this is typically an average of 3-6 months. Experts can run the check for specific drugs or can test the hair for several drugs or classes of drugs. Some of the common checks run are for marijuana, amphetamines, including methamphetamine, MDMA (ecstasy), and MDEA (eve), cocaine, opiates such as heroin, codeine & morphine and also phencyclidine (PCP).

This is a trusted source because while the drugs may have exited the body in the given time frame, this test can still prove the consumption even after a considerable time has passed. While it can’t pinpoint the exact date of drug use (hair growth rate varies from person to person), it can nevertheless establish a fair fact. Also, hair styling products and hair care routine don’t hamper with the test results. Drug testing may be done in criminal investigations, for employment purposes, legal or medical purposes etc. The capabilities and spheres of usage it offers are a multitude.

Hair Tissue Mineral Analysis (HTMA) is one again such test that has a great impact on forensic studies and offered in India exclusively by RichFeel. Analysing the level of heavy metals, toxins and key minerals help deduce much about the person being tested – offering much-needed evidence in crucial criminal investigations. It can also help establish genetic disorders and family links. There have been instances even in very recent times when rulings were made on the basis of such specific key evidence. Do read more about HTMA on our pages, to understand it better.

Here’s a brief on how such hair analysis scores above all other tests when it comes to forensic studies.

How does hair analysis score above others?

  1. Hair specimens can be collected more quickly and easily than blood, urine or any other tissue, using a non-invasive method.
  2. Hair analysis is more cost-effective than mineral testing conducted through other means.
  3. Unlike blood, hair is less susceptible to the homeostatic mechanisms that quickly affect trace element levels.
  4. Long-term deviations of mineral retention or losses are more easily detected in hair than blood.
  5. Concentrations of most elements in the hair are significantly higher than that found in the blood and other tissues.
  6. Hair provides a record of past as well as present trace element levels, ie, biological activity.
  7. Hair provides information on substances entering the hair from the blood serum as well as from external sources.
  8. Hair is invaluable in the assessment of toxic metal levels.
  9. Reliable data on more than 35 nutrient and toxic minerals, and over 25 important mineral ratios.
  10. When performed through reputed clinics, you get a professional interpretation of test reports that can be trusted.

Now having discussed this all, we must understand that hair is a very complex matrix. Thus, the analytical processing often requires critical laboratory tests and it has to be performed through specialised, reliable institutions. A few cases even demand highly sensitive techniques as a positive result in a forensic context has legal implications, and producing falsely-positive reports can lead to mayhem.

Extreme care must be followed in the interpretation of the obtained results after hair analysis, as consequences of such a result may not only have serious implications on the examinee’s life but also put the laboratory or source of analysis under a negative impression.
Yes, it is indeed a proud feat of scientific and technological advancement. It offers great powers. But as our comic superheroes wisely remind us, ‘with great power comes great responsibility’!!

With that, we sign off today! Trust you have gathered some very intriguing hair trivia!

Do also catch up on our other blogs related to hair care, hair loss, treatments & solutions, and more such interesting hair trivia.

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