Fingerprints are the impressions formed on the fingers and thumbs of the individual in the womb. They are unique to every individual since every individual grows in a different intra-uterine environment including twins. Hence, these are extremely helpful in the identification of individuals.
Fingerprints have been found to be extremely helpful to capture criminals as they leave their fingerprints at every place they touch barehand. They are even helpful in identification of a dead body by simply picking the prints from the dead person.
For many years, science has relied upon fingerprints to identify individuals and also solve criminal cases as they are quite reliable and doesn’t vanish easily off from the finger. They even remain until the human body decomposes completely.
Extraction fingerprints from the dead body is important in Mass Disaster cases, Homicidal cases, Accidents, Suicidal cases, etc. Therefore, it is crucial to extract the prints with extreme care depending on the human condition.
Preliminary Examination of a Dead Body
Before recording the fingerprints of the deceased, a visual examination of the hand is
accompanied so as to determine whether the subject’s hands are clean or soiled.
In case the hands are coated with dirt, debris, or any other contaminant then the fingers are first
cleansed. Care must be applied so that the ridges are not compromised during cleansing. The hand needs to be dipped in soapy water or alcohol, depending on the nature and extent of adhering material.
The fingers are blotted with a clean, lint-free paper towel or cotton. Wipes soaked with Isopropyl alcohol may also be used. At times, the hands may be immersed in hot water for a few minutes. This not only assists the skin to dry quickly but also makes the fingers more flexible.
Method of Recording a Fingerprint
Three different stages of the corpse need to be considered:
- Recent Death Stage
- Rigor Mortis Stage
- Decomposition Stage
Stage 1: Recent Death Stage
a) Fingerprint pad method: The imprints of a corpse may be recorded using a fingerprint pad. The finger is rolled over the pad and then the inked finger is rolled over the appropriate box of the fingerprint index card. This method may be tried out only if the fingers are sufficiently flexible.
b) Fingerprint ink method: If the fingers of the corpse are only moderately flexible. A drop of fingerprint ink is placed over a spatula and spread out using an ink roller. The spatula is then used to apply ink consistently to the fingertip. A fingerprint card is next placed in a fingerprint spoon.
c) Fingerprint powder and tape method: If the fingers are quite stiff, the fingerprint powder and tape methods are commonly used. In this method, mostly black fingerprint powder is applied to the fingertip with the aid of a camel hairbrush. The quantity of the powder should be sufficient to cover the entire pattern area. Any excess is blown off. A piece of fingerprint lifting tape is pressed firmly against the fingertip. The tape piece is removed and pasted over the appropriate box of the index card.
Hence, the entire ridge pattern is reproduced by this method.
Stage-2: Rigor Mortis State
If the body has remained in a state of rigor mortis for a long duration, the skin of the fingers becomes shrunken and wrinkled. In such cases, a suitable fluid must be injected beneath the skin, so as to remove the wrinkles and to restore the fingers to their original shapes. Hot water and melted paraffin wax may be used for this purpose. However, a mixture of gelatin and glycerin in the ratio 1:7 has been found effective too.
Each finger is immersed in a separate vessel. Once the fingers have been restored to their original lengths, these are removed from the solution. This may take 4-10 hours. The amputated fingers are then washed with distilled water and then soaked in 1% formaldehyde solution.
Stage-3: Decomposition Stage
The skin of a corpse that has started decaying is the most difficult one to handle, as far as retrieving fingerprints is concerned. In such cases, normally only a small part of the ridge pattern perseveres. The pattern bearing skin of fingertips is peeled off and placed in a solution of formaldehyde. The skin fragment of each finger is immersed in a separate container. Formaldehyde not only retards further decomposition of the skin fragment but also hardens it.
The rolled impressions are recorded using the fingerprint pad method. In some cases, the outer surface of the epidermis is broken down and the ridge characteristics are blurred. However, the ridge design on the undersurface of the skin may still persist.
In such cases, the skin is first loosened from the flesh by boiling in water. Thereafter, the skin is peeled off and placed on cardboard with the inner surface turned outward.