The gun used to kill a 32-year-old woman on San Francisco’s waterfront was stolen from a federal Bureau of Land Management agent in a car burglary in June, sources close to the investigation said Tuesday.

The .40-caliber pistol was stolen from the agent not long before Kathryn Steinle was shot to death July 1 at Pier 14 on the Embarcadero, said one source, speaking on condition of anonymity because he was not authorized to talk about the case publicly.