NCJ Number
217645
Journal
Journal of Forensic Sciences Volume: 52 Issue: 2 Dated: March 2007 Pages: 320-329
Date Published
March 2007
Length
10 pages
Annotation
This study examined the interactions of several acid prewashes and water rinses used on paper that bears latent prints, prior to subjecting the prints to a silver physical developer (PD).
Abstract
The study found that malic acid prewashes led to better fingerprint development than nitric acid washes for nearly all the paper types examined. These results were consistent across different fingerprint donor ages and sex. Low background development was better for nitric acid washes for about half of the papers tested. The concentration of the acid washes should be approximately 2.5 percent for malic acid or at least 0.24 percent nitric acid. A pH monitoring study indicated that malic and nitric acids had different abilities in neutralizing CaCO3 in paper. Rinse steps between the acid wash and the PD steps were not required. The acid wash alone was apparently sufficient to neutralize the paper. The first part of the study examined the difference between the use of malic acid and nitric acid in the acid wash step. The study then determined the concentration level of acid that gave reliable and reproducible results for the process. After the acid concentration experiment, the pH level of the acid solutions was determined in order to obtain further data on the acid-washing process. Next, the study examined the use of water to rinse the paper between acid washes and before the addition of PD. The final stage used scanning electron microscopy energy-dispersive X-ray spectroscopy in order to examine paper samples from previous experiments. This step monitored the levels of calcium in the papers. 10 figures, 2 tables, and 5 references