A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfaces such as glass or metal. Deliberate impressions of entire fingerprints can be obtained by ink or other substances transferred from the peaks of friction ridges on the skin to a smooth surface such as paper.
Fingerprint records normally contain impressions from the pad on the last joint of fingers and thumbs, though fingerprint cards also typically record portions of lower joint areas of the fingers. Human fingerprints are detailed, unique, difficult to alter, and durable over the life of an individual, making them suitable as long-term markers of human identity.
Their use as evidence has been challenged by academics, judges and the media. There are no uniform standards for point-counting methods, and academics have argued that the error rate in matching fingerprints has not been adequately studied and that fingerprint evidence has no secure statistical foundation. Fingerprints are impressions left on surfaces by the friction ridges on the finger of a human.
Fingerprint matching considers only the obvious features of a fingerprint. A friction ridge is a raised portion of the epidermis on the digits fingers and toes , the palm of the hand or the sole of the foot, consisting of one or more connected ridge units of friction ridge skin.
These unique features are formed at around the 15th week of fetal development and remain until after death, when decomposition begins. These epidermal ridges serve to amplify vibrations triggered, for example, when fingertips brush across an uneven surface, better transmitting the signals to sensory nerves involved in fine texture perception. Consensus within the scientific community suggests that the dermatoglyphic patterns on fingertips are hereditary.
