Fingerprints (Dactylography): Identification of a Dead Person

The most accurate and reliable method of identification.

A finger print means an impression made by the ball of the finger.

It is based on the principles that the skin of the balls of the fingers and thumb is covered with papillary ridges with pores of the sweat glands.

Medico-legal importance of fingerprints

1. Fingerprints are absolutely individual, the patterns of the fingerprints are so complex that no two prints from different persons are the same, and even identical uniovular twins have different prints. The incidence of similarity is 1/64 millions.
2. They develop during the intrauterine life (at 16th week) and remain constant throughout life.
3. They are present in the dermis as well as in the epidermis and cannot be altered except in the following conditions:
• Transitory absence due to exposure to ionizing radiation.
• Permanently destroyed in some chronic skin diseases (as leprosy and scleroderma), lost in surgical removal, chemical destruction and by LASER (leaving no scar for identification).
4. They can be obtained even from putrefied and immersed bodies (impression from the separating skin or underlying dermis)
5. Fingerprints can be easily recorded and transmitted from one place to another by a code message.
6. Poroscopy: Is the examination of the pores of sweat glands for their number, pattern, shape, size, etc. It is of value when only a part of the finger print or a fragmentary print is available and the whole finger print is not available for examination.

Types of fingerprints

a. Arches:

Here, the ridges go from one side of finger to the other

b. Loops:

The ridges here make a backward turn in their course from one side to another. It is divided into 2 subgroups; ulnar and radial.

c. Whorls:

Some of the ridges make one or more complete turn.

d. Composite:

Combinations of two or more of the previous types are found in a single print.

Finger prints are compared for numerous ridge characteristics (more than 12) which occur throughout the length of the ridges as bifurcation, trifurcation, dots, island, bridge & angle.

Category: Forensic Medicine Notes