Tragedy At Washington Navy Yard

A 34-year-old contractor opens fire at a Washington Navy Yard Monday and kills twelve people. CNN's John Berman reports.

The chaos started just after 8 a.m., when authorities say Aaron Alexis from Fort Worth, Texas, used his military contractor I.D. to get into a building at the Washington Navy Yard, walked to an atrium and began firing.

But who is Aaron Alexis? CNN's Pamela Brown says the subcontractor entered building 197 legally with an intent to kill armed with three weapons.

Alexis was born in Queens, New York, and joined the Navy as a reservist in May 2007.  According to pentagon officials, he was discharged in January 2011 following a"pattern of misconduct."

While it's unclear what that misconduct was, he did have several run-ins with the law.

Alexis was arrested in Seattle in 2004 for shooting out the tires of another man's vehicle, described in the police report as an anger-fueled "blackout."  His father said his son was suffering from PTSD after helping post 9/11 rescue efforts at ground zero.

In 2008, he was cited and briefly jailed for  disturbing the peace in Georgia.

And he was arrested again in 2010 for discharging a gun in public in Fort Worth, Texas, where he lived until recently. He was never charged in that case.

One of Alexis's friends in Fort Worth, Kristi Suthamtewakul, said he was locked in a financial dispute with the company that contracted him to work for the Navy .

"He did some civilian contract stuff or maybe government contract stuff in Japan for about a month  and then he came back over here.  I was excited because I was the one that picked him up from the airport and he's like a brother to me.  After that, he just didn't feel like he was getting paid the correct amount, or just issues with that."

A motive for the massive shooting is still unknown.

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