The same gun was used to shoot at the Pentagon, a Marine Corps museum and a vacant Marine recruiting station in northern Virginia, the FBI said Thursday.
Evidence from the FBI laboratory in Quantico, Va., links all three after-hours shootings, the agency said.
No one was injured in any of the incidents, which all involved shots fired into vacant parts of the buildings. Investigators haven't determined a motive or identified a suspect.
Shots were fired at the National Museum of the Marine Corps on Oct. 17. Two days later, bullet holes were found in the Pentagon.
Shots were also fired at a Marine Corps recruiting station in Chantilly, Va., late Monday night or early Tuesday.