The gunman who killed 12 people before being shot dead by police in a military complex in the heart of Washington has been described as a young man with an interest in Buddhism and flashes of rage.
Officials today said he had serious mental issues as well.
Aaron Alexis' motive remained a mystery. But US law enforcement officials told The Associated Press that he had paranoia and a sleep disorder and was hearing voices in his head.
The officials also said there has been no connection to international or domestic terrorism, and investigators have found no manifesto or other writings suggesting a political or religious motivation.
Yesterday's attack was the deadliest on a military installation in the US since 2009 and a reminder of the country's long debate over guns. "Yet another mass shooting," President Barack Obama said.
Family members told investigators that Alexis, 34, was being treated for his mental issues. He had been treated since August by the federal Veterans Administration, the officials said. They spoke on condition of anonymity because the criminal investigation was continuing.
The Navy had not declared its defense contract employee mentally unfit, which would have rescinded a security clearance that Alexis had from his earlier time in the Navy Reserves.
Alexis used a valid pass to get into the Washington Navy Yard. In the past, he had complained about the Navy and being a victim of discrimination and had several incidents with law enforcement, including two shootings
Alexis carried three weapons in the attack: an AR-15 assault rifle, a shotgun, and a handgun that he took from a police officer at the scene, according to two federal law enforcement officials who spoke on condition of anonymity because they were not authorised to discuss the investigation.
