The Effect of DNA Evidence on Incidence of Property Crime Arrests

Abstract

Background: With a high volume of incoming cases and ever-present backlogs, forensic laboratories are often limited with the funding and resources necessary to test every evidence item waiting to be processed.1 Properly allocating resources can be a persistent challenge.
Aim: The purpose of this study was to determine which types of physical evidence collected from property crime scenes, upon the completion of deoxyribonucleic acid (DNA) analysis, would most likely lead to cold hits in the Combined DNA Index System database (CODIS) and ultimately result in arrests. The goal here is to provide law enforcement agencies and forensic laboratories with useful information that could improve evidence processing methods and allow them to better utilize limited resources.
Materials and Methods: All of San Diego Police Department’s DNA cases from property crimes during a one-year period were reviewed to determine which evidence types yielded the highest number of arrests. Bloodstains, drinking containers, cigarette butts, clothing, rocks, and various types of tools were the most common types of evidence submitted for DNA testing in property
crime investigations.
Results: Bloodstains resulted in the highest amount of cold hits (73%) and yielded nearly 250% more arrests than non-blood evidence.
Conclusion: When allocating resources in forensic laboratories, property crime cases with blood evidence should be given the highest priority. Further prioritization based on evidence type, however, is not definitively supported by the results of this study.