A fingerprint is an impression of the friction [?] of all or any part of the finger.



Arch Fingerprint


A friction ridge is a raised portion of the [?] .

Fingerprints may be deposited in natural secretions from [?] in friction ridge skin. [?], oil and grease, can be transferred to the surface of an item when friction ridges come into contact with the surface of the item. Fingerprints may also be made by using black printer's ink transferred from the peaks of friction skin ridges to a smooth surface such as a fingerprint [?].

The factors which affect friction [?] impressions are many, and include pliability of the skin, the pressure applied, slippage, and the nature of the surface.

Fingerprint [?] is the process of comparing impressions from fingers or palms to determine if the impressions are from a suspect's finger or [?]. The flexibility of friction ridge skin means that no two fingerprints are ever the same.





Whorl Fingerprint


There are three basic fingerprint patterns: Arch, [?] and Whorl. There are also more complex classification systems that break down patterns to plain arches or [?] arches. Loops may be [?] or ulnar, depending on the side of the hand the tail points towards. Whorls also have classifications including plain whorls, accidental whorls, double [?] whorls, and central pocket loop whorls.

A new technique has been developed to allow fingerprints to be detected on metallic and electrically conductive surfaces without the need to develop the prints first. The technique involves the use of an instrument called a Scanning Kelvin [?] (SKP), which measures the voltage at intervals over the [?] of an object . These measurements can then be mapped to produce an [?] of the fingerprint.