The mother of Washington Navy Yard gunman Aaron Alexis apologised to the victims on Wednesday and was unable to explain what drove her son to open fire on civilian workers inside a restricted military installation.
"I don't know why he did what he did, and I'll never be able to ask him why. Aaron is now in a place where he can never do harm to anyone, and for that I am glad," Cathleen Alexis said in an audio statement aired on MSNBC from her home in New York.
"To the families of the victims, I am so, so very sorry that this has happened. My heart is broken." All 12 victims, aged 46 to 73, were civilians caught up in the shooting spree on Monday morning by the former Navy reservist, who received security clearance to work as an information technology contractor at the site despite a history of misconduct and signs of mental illness.
Alexis, 34, was killed in a gun battle with police officers. With his motive still a mystery, US Defense Secretary Chuck Hagel acknowledged there were "red flags" before Alexis received security clearance.
"Obviously when you go back in hindsight and look at all this, there were some red flags - of course there were," Hagel told a news conference. "And should we have picked them up? Why didn't we? How could we have? All those questions need to be answered."
The government Office of Personnel Management (OPM) acknowledged on Wednesday that during a 2007 security check of Alexis it had uncovered a 2004 arrest on a charge of malicious mischief, but said that the Pentagon decided to grant him clearance anyway.
The OPM declined to give further details, but Alexis was arrested for malicious mischief in 2004 in Seattle when police said he shot the tires of a construction worker's car with a Glock .45-caliber handgun. Alexis later described the incident as anger-fueled "blackout," according to a police report.
The case was never prosecuted. In 2010, Alexis was arrested for shooting through the roof of his apartment and into a neighbor's home, but charges were dropped when authorities determined it was an accident.
More recently, the US Department of Veterans Affairs said Alexis twice visited VA emergency rooms for insomnia but never sought care from a mental health specialist and denied he suffered from anxiety or depression.
Alexis received medication for insomnia in Providence, Rhode Island, on August 23 and Washington on August 28. "On both occasions, Mr. Alexis was alert and oriented, and was asked by VA doctors if he was struggling with anxiety or depression, or had thoughts about harming himself or others, which he denied," the VA said in a statement.
A few weeks earlier, on August 7, Alexis told police while on a business trip to Newport, Rhode Island, that he had trouble sleeping because he was "hearing voices."
He believed people were following him and "sending vibrations into his body," according to a Newport police report. Newport police found his behavior so odd that they called Navy police to alert them and sent them a copy of their report. The Navy said it was looking into the Newport incident.
Bought shotgun in Virginia
Alexis, who was a resident of Fort Worth, Texas, legally bought the 12-gauge Remington shotgun used in the rampage for $419 at the Sharpshooters Indoor Shooting Range and Pro Shop in Lorton, Virginia on Saturday, the store's lawyer, J Michael Slocum said on Wednesday.
Slocum said the store refused to sell Alexis a handgun. "He asked about buying a handgun but was told, no he couldn't buy a handgun because he's not a Virginia resident. At that point, he bought the shotgun," Slocum said.
He said Alexis rented an AR-15 assault rifle and fired it at a store shooting range, and then bought the shotgun along with two boxes of ammunition. According to store employees, he did not ask to buy an AR-15, Slocum said.
Alexis brought a shotgun into the Naval Sea Systems Command building and grabbed at least one handgun once inside, investigators said, opening fire from the fourth floor atrium on helpless victims in a cafeteria below.
Investigators have a "working theory" that Alexis arrived at the building with the shotgun barrel removed, entered a men's room with his bag or backpack, and assembled it, according to a source close to the investigation.