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It's MORNING EDITION, from NPR News. Good morning. I'm Steve Inskeep.
RENEE MONTAGNE, HOST:
And I'm Renee Montagne. Investigators face three, interrelated questions about Aaron Alexis, indentified as the man who killed a dozen people at the Washington Navy Yard.
INSKEEP: One question is how he got on to the base. Another is how he obtained a gun. A third question - and possibly the hardest - is what was happening inside his head.
MONTAGNE: In the past day, clues have emerged about all these questions. One clue is a police report from last month. NPR's Brian Naylor reports.
BRIAN NAYLOR, BYLINE: Last Aug. 7th, police in Newport, R.I., responded to a harassment call at a Marriott Hotel. According to the police report obtained by NPR, the call came from a man whom NPR has confirmed was Aaron Alexis. He told police he had gotten into an altercation with someone at the airport, and that that person sent three people to follow him and keep him awake. He said the three were talking to him through the floor and the ceiling, using some sort of microwave machine to send vibrations into his body.
At a briefing for reporters yesterday, assistant director of the FBI's Washington field office, Valerie Parlave, said authorities still haven't determined why Alexis opened fire in Building 197 at the Navy Yard Monday, but they're looking into his background.
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NAYLOR: Authorities have determined that Alexis entered the Navy Yard using his own valid pass. He had a security clearance, which he took with him, as is common practice when he was honorably discharged by the Navy in 2011. Alexis received his honorable discharge through a program one military official told NPR was a speedy way to get rid of someone not making it as a sailor.
After leaving the Navy, Alexis worked for a time at Happy Bowl, a Thai restaurant in North Texas. Kristi Kinard Suthamtewakul, whose husband runs the restaurant, spoke to member station KERA.
KRISTI KINARD SUTHAMTEWAKUL: He was an unhappy vet, let's just put it that way. He felt slighted by benefits; he felt slighted by the government. He wanted to move to Thailand and then the last I heard, he had changed his mind. He'd been wanting to do that for two years.
NAYLOR: Authorities believe Alexis arrived in Washington late last month. Last Saturday, he traveled to Lorton, Va., where he rented a rifle and used a shooting range. According to a statement from the range owner, Alexis then bought a shotgun and two boxes of shells, after passing a federal background check.
The FBI says he used a shotgun Monday. A federal source says investigators have surveillance video showing Alexis going into a bathroom with a bag, and coming out with a shotgun; supporting a theory that he took the weapon onto the base disassembled, and put it together there. He may also have obtained a handgun, possibly from one of his victims inside the base. But the FBI says Alexis did not have an AR-15 semiautomatic rifle with him, as in earlier reports.
Police responded quickly after the first shots were heard Monday. Washington Police Chief Cathy Lanier.
CHIEF CATHY LANIER: Within seven minutes, we had at least two units - and possibly four units - outside of the building where the shooter was, that could hear - actually, the - another round of gunfire. And they entered immediately, upon hearing that gunfire.
NAYLOR: She estimates it was more than 30 minutes before Alexis was killed by police. At the Navy Yard yesterday, Lt. Cmdr. RoDeece Dean was one of the essential personnel allowed to return to the base. As investigators and law enforcement personnel combed through the facility, Dean said it was not easy getting back to work.
LT. CMDR. RODEECE DEAN: Coming back after an event like this, is difficult. It's something we're still trying to process. And it was difficult to try and sort out what to do first - and what was more important, and what was less important.
NAYLOR: Dean says he was prepared for danger when he served in Iraq. But he says you wouldn't expect to find it in an office building in the nation's capitol.
Brian Naylor, NPR News, Washington. Transcript provided by NPR, Copyright NPR.