Medico-legal importance of hair examination

1. Personal identification such as:

• Sex identification: appearance and distribution of the chest hair, beard and moustache and by detection of sex chromatin & Y-chromosome in cells of hair root.

• Estimation of age: length of the scalp hair in a full term infant is about 3 cm. Growth of the pubic and axillary hair at puberty and grayness of hair in old

• Recognition of race from the form, color and arrangement of the hair (as mentioned before)
  

• Examination of genetic markers from nucleated cells in the root sheath.

2. Identification of the suspected assailant 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 case of rape the assailant may have on his private parts some hair derived from the victim.

3. Identification of the weapon used in certain crime:

• From the manner of cutting or crushing the hair.
• By comparison of the hair present on the instrument with the victim's hair.
• Victim hair may be found on the vehicle in case of hit & run accidents.

4. Differentiation between incised wound (hair is sharply cut) and contused wound (hair is crushed).

5. Distinction between dry burns (singed hair with clubbing), scalds (wet hair) and corrosive burn (wet & eaten up).

6. Diagnosis of firearm injuries and estimation of the distance of firing (singed hair and presence of powder marks).

7. Diagnosis of poisoning and its chronicity:

• Heavy metal poisons are deposited in the hair, starting from the root and extending to the tip. Chemical analysis of the hair helps not only for identification of poisoning but also gives an idea about the time of exposure (hair fibres grow 0.4 mm/day).

8. Examination of the hair tip gives an idea about the time since it has been cut:

• Acute angle when recently cut.
• Rounded end after few days.
• Tapering end after 2 weeks.

9. Examination of the hair root denotes whether it has been pulled out by force (healthy root with ruptured sheath) or has fallen by itself (degenerated root).

Category: Forensic Medicine Notes