Senior law enforcement officials identified the gunman as Aaron Alexis, 34. He was identified through his fingerprints.
According to the Navy, Mr. Alexis enlisted as a full-time reservist in May 2007 and left the service in January 2011. He served as an aviation electrician, and the highest rank he achieved was mate third class. From February 2008 to January 2011, he was assigned to Fleet Logistics Support Squadron 46, in Fort Worth.
Shortly after 4 p.m., the F.B.I. released a “Seeking Information” bulletin asking for the public’s help in learning more about Mr. Alexis. The bulletin, which had two photographs of Mr. Alexis, said that he was born in Queens and was 6 feet 1 inches tall and weighed 190 pounds.