Fingermark Evidence Evaluation Based on Automated Fingerprint Identification System Matching Scores: The Effect of Different Types of Conditioning on Likelihood Ratios

• NCJ Number: 246544
• Journal: Journal of Forensic Sciences Volume: 59 Issue: 1 Dated: January 2014 Pages: 70-81
• Author(s): Ivo Alberink Ph.D.; Arent de Jongh Ph.D.; Crystal Rodriguez M.Sc.
• Date Published: January 2014
• Length: 12 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

In recent studies, the evidential value of the similarity of minutiae configurations of fingermarks and fingerprints, for example expressed by automated fingerprint identification systems AFIS, is determined by likelihood ratios LRs.

Abstract

In recent studies, the evidential value of the similarity of minutiae configurations of fingermarks and fingerprints, for example expressed by automated fingerprint identification systems AFIS, is determined by likelihood ratios LRs. The paper explores whether there is an effect on LRs if conditioning takes place on specified fingers, fingerprints, or fingermarks under competing hypotheses: In addition, an approach is explored where conditioning is asymmetric. Comparisons between fingerprints and simulated fingermarks with eight minutiae are performed to produce similarity score distributions for each type of conditioning, given a fixed AFIS matching algorithm. Both similarity scores and LRs are significantly different if the conditioning changes. Given a common-source scenario, LRs resulting from asymmetric conditioning are on average higher. The difference may reach a factor of 2000. As conditioning on a suspect's fingerprint is labor-intensive and requires a cooperating suspect, it is recommended to just condition on the number of minutiae in the fingermark. Abstract published by arrangement with Wiley.