AARON Alexis, who gunned down a dozen people at the Washington Naval Yard, was a former sailor with a troubled past and anger issues.

Alexis, 34, is reported to have used guns in moments of anger but was also known as a quiet man who meditated regularly at a Buddhist temple in Texas and had taught himself Thai.

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The defence contractor was killed in a gunfight with police, who have not yet speculated as to a motive for the shooting, which also left several people hurt.

The New Yorker told police after a 2004 shooting incident in Seattle that he was present during “the tragic events of September 11, 2001″ and described “how those events had disturbed him.”

Detectives later spoke with Alexis’ father, who lived in New York at the time, who told police Alexis had anger management problems associated with Post-Traumatic Stress Disorder, and that Alexis had been an active participant in rescue attempts on September 11th, 2001.

Born in New York, Alexis served in the military from 2007 until 2011, the US Navy said.

"There is definitely a pattern of misconduct during his service,'' a US military officer said.



The officer did not yet know if Alexis had been dishonorably discharged and could not provide details of his work as a defence contractor.

But The Washington Post reports that Alexis had been working as a computer contractor for The Experts, and appeared to have a government contractor access card that would have allowed him onto the Navy Yard and other military installations, according to the company’s CEO, Thomas Hoshko.

He was working as an hourly technical employee on a massive subcontract with Hewlett Packard to refresh computer systems worldwide at Navy and Marine Corps installations.

Alexis worked for The Experts starting in September 2012 until the end of last year on a Navy computing contract in a base in Japan. From January to July of this year, Hoshko said, they believe Alexis was going back to school.

He was slated to start working on another phase of the Navy computing contract at the Navy Yard this month and already had his government contract access card (CAC) and security clearance that had been updated in July.

Three years before he enlisted, Alexis was arrested in Seattle for shooting out the tyres of a car in what he later told detectives was an anger-fueled blackout after construction workers had "disrespected him.''

He told police that he could not remember firing his gun until about an hour after the incident, according to a police report posted online by the Seattle police.

"From the outside, he was a quiet person,'' J. Sirun, an assistant to the monks at the Buddhist temple Alexis attended in Texas, told the Washington Post.

"But on the inside, I think he was very aggressive. He did not like to be close with anybody, like a soldier who has been at war.''

While he was the kind of man who'd help others carrying heavy things, at least one worker at the Wat Busayadhammavanaram Meditation Center avoided him because he seemed so tightly wound, Sirun told the paper.

"I didn't think he could be this violent,'' Sirun said. "I would not have been surprised to hear he had committed suicide. But I didn't think he could commit murder.''

A former roommate who described Alexis as his ``best friend'' was shocked by the news.

"I don't think he'd do this,'' Nutpisit Suthamtewakul, owner of Happy Bowl Thai, told the Fort Worth Star Telegram.

"He has a gun, but I don't think he's that stupid. He didn't seem aggressive to me.''

Alexis was a “hardcore drinker,” he said, and was also skilled in first-person shooting videogames, which he would play for marathon sessions that lasted hours.

Mr. Suthamtewakul said he and his family would sometimes bring Mr. Alexis plates of food during his videogame binges.

A former landlord, who also frequents the temple, was also stunned by the news and said he'd never seen Alexis get angry about anything.

"Oh boy, I can't believe this,'' Srisan told the Star Telegram. "He was always very polite to me.''

Srisan said he doesn't know why Alexis left the navy. They spoke about it only once, and it was a brief conversation, he said.

"I asked him, 'Why you quit the job with the government?''' Srisan told the Washington Post.

"He said somebody doesn't like me.''

Alexis spent the bulk of his military career in a fleet logistics support squad in Fort Worth, rising to the rank of Aviation Electrician's Mate, third class, the Navy said.

He received two common awards during his service: the National Defence Service Medal and Global War on Terrorism Service Medal.

The Seattle incident was not the only time Alexis was in trouble with the law, according to a police report posted on the Star Telegram's website.

An upstairs neighbor, who told police she was "`terrified'' of Alexis after a longstanding dispute over noise, called for help after a bullet flew up through her floor one evening.

Alexis told police the gun went off accidentally while he was cleaning it and that he didn't think it went all the way through the ceiling because he couldn't see any light through the hole.

He was booked on suspicion of recklessly discharging a firearm but never formally charged.