A year after police used a genetic database to help identify a suspect in the Golden State Killer case, the same technique has been used to arrest dozens of people. Now, for the first time, one of those cases is headed to trial. In Part 1 of a two-part series, we look at the tool that is transforming law enforcement and testing the limits of privacy. Guests: Heather Murphy, a New York Times reporter, spoke with Curtis Rogers, a creator of the genealogy website GEDMatch; Peter Headley, a detective with the San Bernardino County Sheriff’s Department; and Barbara Rae-Venter, a genetic genealogist. For more information on today’s episode, visit nytimes.com/thedaily.

Background reading:

• Using a technique that relies on DNA submitted to online genealogy sites, investigators have solved dozens of violent crimes. But some question the ethics and legality of the technique.
• GEDMatch, a free site that began as a side project, has upended how investigators across the country are approaching cold cases.
• Read about how genetic sleuthing through GEDMatch helped a woman who had been kidnapped as a child recover her identity.