The most important evidence found at the crime scene is a chance fingerprint. A fingerprint is an impression of the ridge outline which appears on the anterior surface of the finger on proximal, middle, and distal phalanges of the fingers and on proximal and distal phalanges of the thumb. Ridges have a definite shape and appear in numerous configurations or patterns, each possessing specific individual details by which positive identification can be made. A fingerprint is an individual characteristic; no two fingers have identical ridge characteristics. Fingerprints do not change over an individual's lifetime, and they have general ridge patterns that permit them to be systematically classified. Some fingerprints are visible to the naked eye, plastic prints are formed when the fingers or the palm come in contact with a plastic body or surface, and latent prints are not readily visible to the naked eye. Procedures for obtaining and processing fingerprints are detailed, along with methods for characterizing and classifying fingerprints. Tips are offered on how to maintain fingerprint records and on how to maximize the physical evidence provided by latent fingerprints. References, tables, and figures