GWEN IFILL: Now more on our lead story, the Washington Navy Yard shootings.
Investigators turned up more details today on the gunman, as the nation's capital honored the dead.
It was a day for mourning and solemn tribute in Washington. Defense Secretary Chuck Hagel and other military leaders laid a wreath at the Navy Memorial in honor of those killed in Monday's massacre.
And at the U.S. Capitol, Senate Majority Leader Harry Reid led a moment of silence for the 12 victims. Officials also released the names of those killed, all of them civilians.
VALERIE PARLAVE, D.C. FBI Field Office: This is a methodical and time-intensive process.
GWEN IFILL: Investigators confirmed today 34-year-old Aaron Alexis, killed by police during the attack, was the lone shooter. Alexis, a Buddhist convert who grew up in New York City, served as a Navy Reservist based in Fort Worth, Texas, for four years. But he was cited at least eight times for insubordination and disorderly conduct.
He was given an early, but still honorable discharge in 2011. Alexis also had repeated run-ins with the law, arrested in Seattle in 2004 for allegedly shooting at a construction worker's car tires and again in 2011 in Fort Worth, accused of firing a bullet through his apartment ceiling.
The FBI's Valerie Parlave said today that Alexis came to Washington last month.
VALERIE PARLAVE: We can say that we have determined Mr. Alexis arrived in the Washington, D.C., area on or about August 25, and he has stayed at local hotels in the area since that time. Most recently, he is known to have stayed at a Residence Inn in Southwest Washington, D.C., starting on September 7.
GWEN IFILL: At the time of yesterday's shooting, Alexis was an employee with a Defense Department subcontractor, The Experts, working on a Navy Yard computer project.
To do his work, he had a valid pass granting him access to the Navy Yard's Building 197, where he opened fire with a shotgun that he brought with him, plus two handguns he took from police. Friends and family expressed disbelief at the news.
KRISTI SUTHAMTEWAKUL, friend of shooter: He just didn't seem like he would be that kind of person that would be that upset enough to go out and do something like this. So, that's why we're confused.
ANTHONY LITTLE, brother-in-law of shooter: He wasn't that kind of a person. I didn't really hear anything that would make me feel like, as a newcomer to the family, that somebody be watching him.
GWEN IFILL: Questions were also raised today over Alexis's mental state. The FBI refused to comment on reports that he'd been treated at Veterans Affairs hospitals far series of problems, including paranoia, a sleep disorder and hearing voices.
The Navy had not declared him mentally unfit. That red flag would have been stripped him of his security clearance. White House Press Secretary Jay Carney said today the administration is already reviewing contractors in the wake of leaks by Edward Snowden at the National Security Agency.
JAY CARNEY, White House Press Secretary: And I can tell you that, at the president's direction, OMB is examine standards for contractors and employees across federal agencies. So this is obviously a matter that the president believes and has believed merits review.
GWEN IFILL: But Pentagon officials also said today Defense Secretary Hagel will order his own security review of Defense Department installations worldwide.
So how did Aaron Alexis gain access to the tightly secured Navy Yard, and could officials have seen it coming?
For the latest details, we turn to Ernesto Londono, who covers the Pentagon for The Washington Post.
Ernesto, thanks for joining us.
Today has been a day full of whys and hows. Let's start with the how. How do we know that he gained access to this installation, which is considered to be very secure?
ERNESTO LONDONO, The Washington Post: Right.
The answer on that front appears to be pretty straightforward, and that is he was working there. He had a legitimate need to be in that building based on the work he was doing as a subcontractor for the Defense Department. The broader question that people are raising is in light of all the troubling information that we found in just a few hours -- and you can find easily by a simple Google search -- why was this man given a security clearance and a military badge that gave him unfettered access to a sensitive facility?
GWEN IFILL: Did we begin to get to the bottom -- the answer of any of those questions today?
ERNESTO LONDONO: Not substantively.
I think people at the Pentagon are determined to do a wholesale review of access at installations worldwide. And there's a huge interest in trying to figure out whether the -- the mechanisms we have in place to screen job candidates and contractors are adequate.
Very troublingly, there was an inspector general's report released today suggesting that the Navy in the past -- in the recent past, has cut corners when it came to vetting people who were requesting access to installations. This report was in the works for some time, and it's not related to this case.
But what investigators found was that the Navy was doing a pretty bad job at screening people. And in at least 52 cases, it gave badges to felons, who are not supposed to be given access to military installations.
GWEN IFILL: Fifty-two cases, that sounds like a lot, especially in light of what we saw yesterday.
But we know that now Secretary Hagel and Secretary of the Navy Ray Mabus, and we heard the president launching all kinds of investigations. Have there been investigations into this sort of access before?
ERNESTO LONDONO: There have.
However, you know, if you look at the serious security breaches that have happened at military installations, sort of the massive shooting incidents, there's two major ones, yesterday's and the 2009 shooting at Fort Hood. And in both cases, they were perpetrated by people who had access to be there in the first place.
So I think the focus will likely be whether there were red flags that were ignored, whether there were people who, you know, knew about the behavioral issues that these two individuals had who could have flagged them somehow. Where there were mental health providers who were in a position to know that these people were unstable and were showing signs of distress? And was that information shared with the proper authorities and could these incidents have been stopped earlier?
GWEN IFILL: A somewhat predictable debate erupted in Washington today about how he may have gotten his weapon. What do we know about how he did?
ERNESTO LONDONO: We know he purchased a handgun at a gun store in Lorton, Virginia, on Sunday. It appears to have been a pretty straightforward transaction.
He went to the store. They did a check on him. They run his name through law enforcement databases. There was no red flag. There was no indication that he's a convicted felon, which would have made him ineligible for a gun purchase. So the gun owner sold him the weapon. Then he walked out of the store with it.
GWEN IFILL: What do we know about his career in the Navy at the time he was serving as a Naval reservist?
ERNESTO LONDONO: Well, I was able to reach one former colleague who said that very early on he was a bit of an introvert, he was somebody who wasn't very outgoing and was kind of quiet and reserved.
In recent years, though, she told me that she saw some troubling changes in his personality. He became very aggressive. He was prone to outbursts of anger when they were out in social settings. He would sometimes just erupt in shouting matches with people around him for causes that didn't really seem to warrant that reaction. He didn't like authority. He was constantly challenging his superiors.
So she told me that, you know, his comrades concluded that he was really not a good fit for the military, because if you're serving, you need to know how to take orders.
GWEN IFILL: And did we get any clarity today on what his motives may have been?
ERNESTO LONDONO: We didn't.
Increasingly, I think we're seeing signs that he had some fairly serious mental health issues. He apparently had complained to authorities that he was hearing voices, behavior that appears to have been delusional, paranoid, from what we have been able to glean from law enforcement sources.
But there is no clear-cut motive. Nobody has really articulated that he had a huge axe to grind with the Navy, that he was furious at the Navy, that there were any individuals working at that the facility that he knew that he may have been trying to settle scores with. So at this point, no rational motive has emerged.
GWEN IFILL: Awfully troubling.
Ernesto Londono of The Washington Post, thank you very much.
ERNESTO LONDONO: My pleasure.