The Effects of DNA Databases on Crime

Every US state has a database of criminal offenders' DNA profiles. These databases receive widespread attention in the media and popular culture, but there has been no rigorous analysis of their impact on crime. This paper intends to fill that gap. I exploit the details and timing of state DNA database expansions in two ways, first to address the effects of DNA profiling on individuals' subsequent criminal behavior and then to address the aggregate effects on crime rates. I show that DNA databases deter crime by profiled offenders, reduce crime rates, and are more cost-effective than traditional law enforcement tools. (JEL H76, K42)