Introduction

The investigating officer often finds hair as evidence at a crime scene. Hair is a type of physical evidence. Physical evidence is anything which is tangible at a crime scene. Hence hair comes under this category.

Hair is also classified under physical evidence as class evidence. Class evidence is material that connects an individual or object to a group. Hair can only act as a class evidence if it has the follicle cell attached to it. Without the follicle cell it cannot help identify a specific person. Hair evidence can easily be found at a crime scene – it can adhere to articles of clothing, carpets, and many other surfaces.

Function of hair on an organism’s body:

1. The hairs on the body help to regulate body temperature. It insulates the body and keeps it warm.
2. It reduces friction, acts as a barrier to sunlight and functions as a sense organ.
3. The temperature regulating function is more effective and efficient in animals than in humans as they have longer, more dense hair.

The structure of hair

Hair strand has 2 regions- a follicle and a shaft.

Follicle: It is surrounded by blood vessels which supply nutrition to hair strand and help it grow. It has a bulb and associated with it is a sebaceous gland which helps keep the hair strand conditioned. It also has certain erector muscles which make the hair stand when there are certain environmental changes.

Shaft: Keratin is the only component of the shaft which is a protein. It helps make the hair strong and flexible. The shaft is 3 layered – inner medulla, a cortex and outer cuticle.

Types of hair found on crime scene

At a crime scene we can find hair from different body parts:

1. Head hair
2. Body hair
3. Underarm hair
4. Pubic hair

   Eyebrow and eyelash

5. Beard and mustache.

Racial differences

The hair have certain characteristics which are peculiar to racial groups. With the help of this we can identify and differentiate between people and aid any investigation. For example – there are certain differences between the European hair and Asian hair. Like European hair are generally straight or wavy, small and evenly distributed. Whereas Asian hair are straight and densely distributed.

Animal and human hair

They have vast differences, including the pattern of pigmentation, the medullary index and cuticle type. Human hairs have denser pigmentation towards cuticle and in animals its towards medulla. Animal hairs have a larger medulla as compared to human hair.

Using hair in an investigation

As discussed earlier, hair can be left at a crime scene due to any kind of contact (Locard’s Exchange Principle). Hair can be collected by plucking, shaking and scrapping different surfaces. It can also be done by sticking tape over a surface so that hair sticks to it.

Vaccuming can also be done. After vaccuming it can be separated from the vaccum’s container. If a number of hair collected are large, one investigator will compare them to the hair samples taken from 6 major regions of victim’s or suspect’s body.

Microscopy

Hair has 2 characteristics – microscopic and macroscopic. Macroscopic characters – length, colour and curliness. Microscopic characters – pattern of medulla, pigmentation of the cortex and type of scales on cuticle.

Typical magnification used to analyse hair sample is – 40x – 400x. This enables us to view the sample in both high and low magnifications. 5. Different microscopies used – phase contrast microscopy, fluroscence microscopy, electron microscopy. Many objects are adhered on the shaft of hair. Ingested or absorbed toxins such as arsenic, lead and drugs can be detected by chemical analysis of hair. During the analysis of hair shaft, it is dissolved into an organic solvent. The solvent breaks the keratin and releases the absorbed substances. Since hair cannot readily decompose, by testing different parts of hair, it may be possible to establish a timeline for when exposures to poisons or other toxins may have occurred. 9. The hair follicle has some blood and tissue attached to it. This is used for DNA analysis.

Case study

Alma Tirtsche (1921)

Alma Tirtsche’s beaten body was found wrapped in a blanket in what is known as Gun Alley in Melbourne, Australia. Because the body was relatively free of blood, the police deduced that she had been murdered elsewhere and brought into the alley. Her body had been wrapped in the blanket. A local bar owner, Colin Ross, was questioned. Ross admitted seeing her in his bar earlier.

Investigators collected blankets from Ross’ home and found several strands of long, reddish blond hair on them. The length of hair implied that they were from a female, and the concentration of pigment in the hair implied a younger woman. Some ends of the hair were irregular, implying the hair had been forcibly broken off. The physical similarity of the hair found on the blanket with that of Alma convinced the investigator that Ross was the murderer.

Eva Shoen (1990)

In Telluride, Colorado, Eva Shoen was found dead from a single gunshot to her head. The police recovered the bullet and expected to solve the case using information from ballistics. Unfortunately, they did not have any useful leads. Three years later, the police received a phone call from a man who believed that his brother, Frank Marquis, was responsible for the murder. A gun was found on Marquis, but he had already tampered with its barrel, preventing a ballistic match.

From questioning, police learned that Marquis had been in Telluride when Shoen was murdered. They also discovered that he had thrown 2 clothing bundles out of the car. On searching they found the bundle and on further investigation found a single strand of hair adhered to it. On analysis it was matched with Eva Shoen’s hair. Marquis confessed of murdering her and was imprisoned for 24 years.