Navy yard gunman Alexis Aaron treated for mental issues

The gunman who killed 12 people before being shot dead by police in a military complex in the heart of Washington is being described as a young man with an interest in Buddhism and flashes of rage. Officials on Tuesday said he had serious mental issues but was not stripped of his security clearance.

Aaron Alexis' motive in Monday's rampage remained a mystery. U.S. law enforcement officials told The Associated Press that he had paranoia and a sleep disorder and was hearing voices in his head.

The officials 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. They spoke on condition of anonymity because the criminal investigation was continuing.

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Officials have said Alexis, a 34-year-old contract employee on a Navy project, used a valid pass to get into the Washington Navy Yard, where 18,000 people work, and started shooting. Witnesses described a gunman firing down on the cafeteria from an upper-floor overlook. Three people were wounded.

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Once burned, twice removed. When the Boston bombings occurred April 15, 2013, the social media site Reddit became the centre of what was later called an "online witch hunt." People speculated publicly at the website on who the bombers might be, naming several possibilities wrongly, as it turned out.

When news of mass shootings at the Washington navy yard broke Monday, police first thought as many as three shooters might be involved. To stop any speculation about their identity and a replay of their Boston bombing experience Reddit banned a section for amateur sleuthing on the case, the Washington Post reported at its website.

"We banned it because it violated site rules by encouraging the posting of personal information," a spokesman told the Post.

Officials said Tuesday Alexis used a shotgun and two handguns in the attach, but not an AR-15 assault rifle, as officials had previously said.

Two law enforcement officials told The Associated Press that an AR-15 was found at the scene. One of them saidTuesdaythat Alexis did not use that weapon in the shootings. It was not immediately clear whether the rifle belonged to a law enforcement or security officer responding to the gun battle.

The official said Tuesdaythe guns that Alexis used included a shotgun he had purchased and two handguns that he took away from a law enforcement officer at the scene.

The attack appeared unlikely to lead to tighter gun controls. Measures proposed during national outrage over a school shooting in December that killed 20 children failed this year in Congress. President Barack Obama said Monday.It was at least the seventh mass shooting of his presidency.

But the rampage is likely to raise more questions about the background checks done on contract employees and others who are issued U.S. security clearances an issue that came up this year with National Security Agency leaker Edward Snowden, an IT employee with a government contractor.

At the time of the shooting, Alexis was an employee with The Experts, a company that was a Defence Department subcontractor on a Navy-Marine Corps computer project, authorities said.

The U.S. law enforcement officials said Alexis had been treated since August by the federal Veterans Administration, and family members told investigators that he was being treated for his mental issues.

The Navy had not declared Alexis mentally unfit, which would have rescinded a security clearance that he had from his earlier time in the Navy Reserves.

In the past, Alexis had complained about the Navy and being a victim of discrimination and had several incidents with law enforcement, including two shootings.

Alexis had been a full-time Navy reservist from 2007 to early 2011, the Navy said. U.S. officials said he had a string of misconduct problems during that time, but he received an honorable discharge.

The officials said Alexis had incidents of insubordination and disorderly conduct and was sometimes absent from work without authorization. The offences were enough to prompt Navy officials to grant him an early discharge through a special program for enlisted personnel.

A convert to Buddhism who grew up in New York City, Alexis had had shooting incidents in 2004 and 2010 in Fort Worth and Seattle and was ticketed for disorderly conduct after being thrown out of an Atlanta nightclub in 2008.

At the time of the rampage, Alexis was an employee with The Experts, a company that was a Defence Department subcontractor on a navy-Marine Corps computer project, authorities said.

Valerie Parlave, head of the FBI's field office in Washington, said Alexis had access to the navy yard as a defence contractor and used a valid pass.

Alexis had been a full-time navy reservist from 2007 to early 2011, leaving as a petty officer third class, the navy said. It did not say why he left. He had been an aviation electrician's mate with a unit in Fort Worth.

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A convert to Buddhism who grew up in New York City, Alexis had had run-ins with the law over shooting incidents in 2004 and 2010 in Fort Worth and Seattle and was portrayed in police reports as seething with anger.

The Washington navy yard is a sprawling, 16.5-hectarelabyrinth of buildings and streets protected by armed guards and metal detectors, and employees have to show their IDs at doors and gates. More than 18,000 people work there.