NCJ Number
243855
Journal
Journal of Forensic Identification Volume: 63 Issue: 5 Dated: September - October 2013 Pages: 571-591
Date Published
October 2013
Length
21 pages
Annotation
Forensic examiners routinely analyze impressions and make determinations, based on their training and experience, of whether the discriminating strength of the features in an impression is such that a decision of identification or exclusion is warranted (e.g., whether the print is of value). Although minutiae quantity is not the sole factor for basing value determinations, it has been found through previous studies to play a major role. Because examiners' training and experience will vary, this study seeks to understand, in general, how examiners' decisionmaking behavior changes when faced with comparisons of friction ridge skin when minutiae quantity varies, but quality remains very high.
Abstract
Although friction ridge skin is widely accepted to be unique, impressions of the friction ridge skin are not perfect reproductions of the skin and therefore will vary in their discriminating strength, depending on the quantity and quality of the minutiae and other features reproduced. The results indicate the decisionmaking behavior is impacted in a predictable manner between inconclusive and identification decisions (for mated sources) based on the number of minutiae present. Eighty percent (80 percent) or more of examiners' decisions were identification for mated sources when seven or more minutiae were present. No further increase in the relationship between examiner decision and minutiae quantity was observed for impressions with more than seven minutiae. These findings correspond well to the sufficiency chart published by the Scientific Working Group for Friction Ridge Analysis, Study and Technology (SWGFAST) in the area pertaining to high-quality impressions. Additionally, there appears to be no relationship between minutiae quantity and erroneous exclusion decisions. When presented with the same comparison twice, nine examiners (17 percent) changed their decision between inconclusive and the correct decision or vice versa. This study provides greater understanding of how minutiae quantity may impact examiners' decisionmaking behavior when faced with high-quality impressions. Although further research is needed with lower quality impressions, the results from this study suggest minutiae quantity may be a factor that forensic laboratories may consider when triaging which impressions should undergo enhanced measures of quality assurance. (Published Abstract)