Using DNA Databases to Track Down the Golden State Killer Suspect

It’s been widely reported that investigators got a break in the East Area Rapist/Golden State Killer case when they uploaded a DNA profile to a genealogy database, GEDmatch, and identified relatives of the suspect, Joseph DeAngelo. Did they get lucky, or did they have a good chance of finding him? UC Davis population biologists Graham Coop and M. D. “Doc” Edge have written a nice explainer of the science behind this search.

DNA overlap between first cousins and their common grandmother (GCBias.org)