A mass-shooting in Annapolis, Maryland, at the Capital Gazette yesterday killed five journalists, making it the most deadly domestic attack on the press since 9/11. Local police say a suspect in custody, Jarrod Ramos, appears to have acted alone and been motivated by retribution for a failed defamation lawsuit against the paper. As accounts of the shooting and its aftermath arrived, one detail stood out: The suspect was uncooperative after apprehension, and the county police used facial-recognition technology to identify him. Some would celebrate the use any available technology to name an unidentified and uncooperative suspect caught in the act of a mass shooting, especially before the incident is clearly contained. But recently, complex surveillance technologies, like a service that Amazon pitched to law enforcement, have come under scrutiny.

Yesterday several police departments in California announced the arrest of the "Golden State Killer," who killed a dozen people between 1978 and 1986 and has been accused of over 50 rapes. At the time, investigators said DNA played a role in identifying former Auburn, CA police officer Joseph James DeAngelo, and today went a step further with the explanation. The LA Times and New York Times report that investigators took DNA samples from the old crime scenes and plugged them into online databases, looking for familiar matches that would help narrow down the suspect. The Olympian reports that by combing through family trees of partial matches they focused on DeAngelo, who was the right age and had lived in some of the areas. Before arresting the subject they got a DNA sample from something DeAngelo had discarded and checked for a match.