TODAY | September 17, 2013
>>> meantime, we're learning more today about the gunman as investigators search for a possible motive. pete williams is covering that part of the story. pete, good morning to you.
>> savannah, good morning. officials say the picture emerging this morning is of ayman with a navy past who had a history of psychiatric problems and who was apparently deteriorating rapidly.
>> reporter: authorities say all the shots were fired by one man. aaron alexis , age 34. a former navy reserve electronics specialist from fort worth texas.
>> we do now feel comfortable that we have the single and sole personal responsible for the loss of life.
>> reporter: just last week investigators say he bought a shotgun from a dealer in virginia, about 20 miles south of washington. they say he was part of a team of civilian subcontractors that checked into this washington hotel near the navy yard to work on a military computer project.
>> he had legitimate access to the navy yard as a result of his work as a contractor and he utilized a valid pass to gain entry to the navy yard .
>> reporter: alexis was born in new york city where he still has family. his brother-in-law in brooklyn said the family is in shock.
>> no one ever mentioned anything about him being aggressive or being this type of way or anything like that.
>> reporter: the owner of a thai restaurant in fort worth , texas described alexis as a peaceful practicing buddhist but another friend says alexis was a devoted player of violent video games .
>> we joked about him being obsessed about those video games at his age.
>> reporter: a fort worth police report says he was arrested three years ago for firing a bullet that went into the apartment above his. he claimed he was cleaning his gun. nine years ago he shot the tires of a car used by workers that parked near his house and police said he did it during a black-out fuelled by anger. police say alexis father told them at the time his son had anger management problems since helping rescue people in new york on 9/11. they say he has undergone a series of treatments at va hospitals for psychiatric problems.
>> they believe they came to the naval yard armed only with a shotgun and then picked up two other weapons, taking one of them from a police officer that he shot.