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Improved Fingerprint Acquisition

NCJ Number
215245
Journal
Law and Order Volume: 54 Issue: 7 Dated: July 2006 Pages: 104-107
Author(s)
Doug Hanson
Date Published
July 2006
Length
4 pages
Annotation
This article reviews the history of methods for visualizing latent fingerprints, with attention to the advantages and disadvantages of recent methods developed.
Abstract
Ninhydrin reagent, which reacts with amino acids in the oil from fingers to produce a blue-purple stain pattern, was an early addition to fingerprint identification. Other chemical methods have followed, including fuming an object with iodine vapor, treating with silver nitrate, or forming metal complexes. In 1990, a new chemical reagent more sensitive for visualizing prints on paper objects was introduced. After processing, this reagent, generally called DFO (1,8-diazafluoreneone) produces a pale print compared to ninhydrin, but is still highly visible under specialized light sources and even room light. DFO prints develop in approximately 30 minutes; whereas, ninhydrin prints may take longer than 24 hours to develop. A number of ninhydrin derivatives have been developed in an effort to increase their ability to enhance latent prints. One of these, 1,2-IND (1,2-Indanedione), is now widely used by many departments. It combines the advantages of both DFO and ninhydrin and is less expensive. A number of fluorescent powders have been developed for print dusting. In order to visualize these prints, they must be viewed under an alternative light source or a laser. The advantages of this approach are its capability of visualizing even weak latent prints at the crime scene, production of a vivid fluorescent color that provides greater contrast to background colors, and more well-defined photographic records. These fingerprints can be seen under room light and outdoors. More recently, lasers have been introduced as light sources for visualizing latent prints. The major disadvantage for both alternative light source devices and a laser detection system is the cost of the equipment, specialized cameras, and lighting equipment required to record the results.