NCJ Number
84446
Date Published
Unknown
Length
0 pages
Annotation
A fingerprint expert describes the comprehensiveness of the FBI's fingerprint records, the agency's three methods of developing latent prints, and the criteria for comparing developed prints with suspects' prints.
Abstract
The FBI maintains 160 million inked fingerprints on file, of which 21 million are individual prints kept in the criminal files and 39 million are in the civil files. The agency receives 24,000 sets of fingerprints each day. It makes latent impressions by reproducing the hand's friction ridges; chemicals are used to develop the print. The iodine fuming method, used in only 1 percent of developing work, will develop oil-based latent prints. Another method heats a solution of ninhydrin crystals dissolved in acetone and sprays it on the document. The ninhydrin method is used in 90 percent of developing work. The solar nitrate method involves dipping the document in a solar nitrate solution and exposing it to bright lights. The FBI employs over 1,300 technicians in handling fingerprints. These technicians analyze latent prints to determine whether a sufficient number of characteristics is present to make a comparison with the suspects' prints. Technicians have the sole responsibility for this determination as no standard exists to serve as a basis of comparison. Normally, 8-10 or more characteristics are seen before positive identification is made. A question and answer session concerns the FBI's fingerprint classification criteria, technical fingerprint comparisons, and additional detail on the fingerprint process.