More Straightforward Derivation of the LR for a Database Search

• NCJ Number: 249338
• Author(s): Charles E.H. Berger, Peter Vergeer, John S. Buckleton
• Date Published: January 2015
• Length: 5 pages
• Agencies: NIJ-Sponsored
• Award: Population Genetic Issues for Forensic DNA Profiles

Annotation

This paper proposes a new, simpler derivation of the likelihood ratio (LR) for a DNA database search.

Abstract

In the comparison of the proposed short and conventional derivations of the LR in four scenarios, the shorter derivations were easier to follow and provided more assistance in understanding the problem. Matching DNA profiles of an accused person and a crime scene trace are one of the most common forms of forensic evidence. A number of years ago the so-called ‘DNA controversy’ was concerned with how to quantify the value of such evidence. Given its importance, the lack of understanding of such a basic issue was quite surprising and concerning. (Publisher abstract modified)