Washington (CNN) - The picture emerging of the dead gunman in Monday's rampage at the Washington Navy Yard is a study in contrasts, one of a man who practiced languages and meditated, and another of a cold-blooded killer.
The gunman was identified as 34-year-old Aaron Alexis, a former Navy reservist and a current military contractor, the Washington FBI Field Office told CNN. His identity was confirmed by fingerprints and a picture ID card, the FBI said.
Authorities have not released a possible motive in the morning shooting at the headquarters for Naval Sea Systems Command that left 12 people -- and the gunman -- dead. But a friend said Alexis was locked in a dispute over money with the company that contracted him to work for the Navy.
Investigators also learned that Alexis had recently made contact with two Veterans Administration hospitals for apparent psychological issues, law enforcement sources told CNN on Tuesday.
Authorities said earlier that they are confident that Alexis was the lone gunman, bringing to an end a daylong police search for a possible second suspect.
Alexis was carrying a military-contractor ID that matched his appearance, a D.C. Metropolitan Police official told CNN on condition of anonymity.
Alexis used that ID to gain access to the Navy Yard, according to a U.S. law enforcement official with knowledge of the investigation.
He drove onto the installation and parked before walking a short distance to Building 197. Once inside, according to the official, Alexis made his way to an overlook above the atrium and opened fire into the cafeteria.