Fingerprints may be left on objects, when touched, through the transference of sweat or fatty matter from the ridges. Each ridge is dotted with sweat pores, and fatty matter may adhere to the ridges in touching the face or hair. Generally these prints are not readily visible and are called latent prints. Such impressions left at the scene of a crime are made visible by the application of powders or chemicals and are preserved for investigative use by photography or through removal by adhesive-surfaced materials.
Finger impressions have been observed on certain ancient documents, but the conclusion that they were used for fingerprint identification is open to controversy. Interest in scientific fingerprint identification started in 1880 with the publication in the English journal Nature of articles by Henry Faulds and William Herschel. It remained for Francis Galton, a 19th-century English scientist, to establish, through long and detailed observation, the individuality and permanence of the finger patterns and to describe a simple system of classification. The first practical, and the most widely used, system of fingerprint classification was devised by E. R. Henry and adopted officially by the British government in 1901. Numerous United States court decisions have upheld the reliability of fingerprint evidence. It is routinely used in the apprehension and prosecution of criminals. Because of the positive nature of fingerprint identification a few criminals have attempted to evade apprehension by mutilating their fingerprints. None of these efforts has been successful
Palm prints and footprints are also useful for identification but, for technical reasons, are not as suitable as fingerprints for systematic filing. The U.S. government and armed forces have fingerprinted their personnel for years, and identification of victims of civil disasters by fingerprints has assumed importance.
