NCJ Number
88839
Date Published
1981
Length
38 pages
Annotation
Although the traditional methods of fingerprint development may prove more effective than the traditional methods, some of the new methods require more technical training than conventional techniques due to the operation and maintenance of complicated and delicate machinery.
Abstract
The conventional methods of fingerprint development are (1) dusting, which relies on the preferential adherence of fine-grained powder to fingerprint residue; (2) iodine fuming, which involves the absorption of iodine fumes by fatty or oily substances present in latent prints; (3) silver nitrate development, which relies on the reaction of the silver nitrate's silver ions with chloride ions of the salt in latent print residue; and (4) ninhydrin treatment which is based on the reaction of the compound ninhydrin with amino acids in latent print residue. Iodine-silver transfer is the most practical conventional method for developing latent fingerprints on skin, and a staining method that uses the compound crystal violet has been successful in identifying latent prints on adhesive surfaces. New techniques of fingerprint development include metal deposition, autoradiography, and laser detection. In thin film fabrication, fingerprint contamination inhibits vacuum deposition of metals on surfaces. This effect can be used to detect latent prints. The development of latent prints through metal deposition consists of vacuum evaporation of metals onto surfaces containing latent impressions. A metal film is deposited at locations that do not contain fingerprint residue. The autoradiography technique consists of incorporating a beta-emitting radioisotope into the fingerprint residue and then bringing the labeled surface in contact with X-ray film, such as Kodak Industrex D. The labeling of latent prints is accomplished either by treating the surface with reagents that contain radioisotopes or by generating radioisotopes in the fingerprint residue through neutron activation. In 1976, a method for detection of latent prints by laser illumination of objects was developed, and a number of adaptations of this method have occurred since then. A discussion of fingerprint classification systems is appended, and 37 footnotes are provided.