Defense officials say Aaron Alexis, identified as the gunman who opened fire at the Washington Navy Yard, was a full-time Navy reservist from 2007 to 2011 and worked recently as a Defense Department contractor.
He also prayed at a Buddhist temple, was taking online course in aeronautics and was involved in past shooting incidents which attracted police attention in Seattle and Fort Worth, Texas.
It was not immediately clear why Alexis left the reserves, who his latest employer was, or what his motives might have been for going on a rampage. He was one of 13 people killed during Monday's shootings.
Police in Seattle say Alexis was arrested there in 2004 for shooting out the tires of another man's vehicle in what he described to detectives as an anger-fueled "blackout."