Aaron Alexis legally purchased the shotgun he used to kill 12 people, the FBI said Tuesday.
FBI Assistant Director Valerie Parlave also told reporters that Alexis only had the shotgun -- not an assault rifle, as many news outlets reported -- when he walked into Building 197 at the Washington Navy Yard on Monday morning. But it may not be the only gun he used.
"We have no information that he had an AR-15 assault rifle in his possession," she said at a press conference. "He may have gained access to a handgun ... after he began shooting."
An initial investigation indicates that Alexis bought a Remington 870 shotgun at a Lorton, Va., gun shop last week, according to the Wall Street Journal. State law in Virginia allows for an individual to buy rifles or shotguns even if that person is not a state resident.
The Glock handgun found on his person after Monday's shooting rampage was likely picked up from a victim, authorities told the Washington Times.
There's still plenty of room for debate about whether Alexis should have been prohibited from making a legal gun purchase, given his criminal history. In May 2004, he was arrested in Seattle for firing three shots into two rear tires of a Honda. At the time, Alexis claimed he had an "anger-fueled blackout" and could not remember the shooting. Still, he did not commit any felonies that would bar him from making a gun purchase.
In 2010, Alexis was charged with a misdemeanor in connection to a shooting at his apartment complex in Fort Worth, Texas. A resident reported that Alexis, who lived below her, shot at her through the floor.
The WSJ also notes his mental health history. Although Alexis recently sought mental health treatment through the Veteran's Administration, a court must decide whether someone is "mentally unfit" to own a gun under federal law.
The ballistics investigation at Building 197 is still fluid, so it remains unclear how many or which guns Alexis used in the shooting.