DACTYLOGRAPHY(FINGERPRINTS)
• Dactylography(taken from two Greek words daktylos meaning 'finger' and graphe in meaning 'to write') refers to fingerprinting.
Dactylography refers to the study of patterns formed by papillary or epidermal ridges present in bulbs of fingertips called fingerprints.
• Fingerprints are formed in the 5th month of intrauterine life.
• It is the most important and accurate method of positive identification.
• Sir William Hershel (in india) and Henry Faulds (in japan) were the first person who started using fingerprints.
Principle :
It is based on the principle that fingerprints are the impression of patterns formed by papillary or epidermal ridges present on the bulbs of fingertips and these patterns are constant for a person and persists throughout the life.
These patterns are identical to a single individual only and do not match even in identical twins.
Each millimetre of papillary ridge contain 9-18 pores which are actually opening of sweat glands. Sweat secreted from these pores when mixed with sebum secreted from sebaceous glands forms impression of fingerprints.
Thus, whenever fingers of a live person come in contact with certain object, it leaves impression on them. This is in accordance with Locard's principle of exchange.
Classification
1. Loops (60-70%)
a. Radial
b. Ulnar
2.Whorls (25-35%)
a. Concentric
b. Spiral
c. Double spiral
d. Almond shaped
3. Arches (6-7%)
a. Plain
b. Tented
c. Exceptional
4. Composite (1-2%)
Types of fingerprints
1. Latent print (chance print) is an invisible or barely visible impression left on a smooth surface.
2. Visible prints are formed by fingers stained with blood or ink or other medium.
3. Plastic print is an impression made in a soft surface such as cheese, soap, mud, pitch, candles, thick dried blood, etc.
Medicolegal Importance
1. The recognition of left at a scene of crime, eg, on weapons, furniture, doors, utensils, clothes, etc establish the identity of the criminal.
2. The identification of suicides, deserters, persons suffering from loss of memory or those dead of unconscious after being involved in an accident and of decomposing bodies.
3. Identification in case of accidental exchange of newborn infants.
4. The prevention of impersonation
5. To maintain identity records.
6. Cheques, bank notes and other legal documents can bear fingerprint.