DNA databases are useful tools for improving public safety. While past research examines the effects of national- or state-level databases, little is known about the distinct benefits of a local, District Attorney-run DNA database. Two key advantages of a local database are that (i) more local criminals submit a sample as part of a plea agreement (submission is not restricted to certain crimes and mandatory) and (ii) response times for identifying reoffenders from DNA evidence are shorter. This report performs a retrospective benefit–cost analysis on the Orange County District Attorney’s DNA database. The analysis is run on administrative records that provide costs, entries into the DNA database, and matches that occur between samples taken from a crime scene and individual profiles in the database. We also estimate the deterrence effect of entry into the database with defendant-case-level data. We find that, for every dollar spent on operating the database over the last 10 years, $1.71 is saved due to the estimated reduction in future offenses.
