The Washington Navy Yard reopened Thursday in an atmosphere of sadness for those lost in Monday's shooting spree, mystery over why it happened and controversy over the law enforcement response to it.
The FBI says Navy contractor Aaron Alexis, 34, assembled a shotgun in a men's room and killed 12 people before he was fatally shot in a gunfight with law enforcement.
FBI Director James Comey said Thursday that Alexis appeared to be moving with "no discernible" pattern as he rampaged through Building 197 of the Naval Sea Systems Command headquarters.
"It appears to me that he was wandering the halls and hunting people to shoot," Comey said.
He said Alexis entered the building and went to the fourth floor, carrying a bag. He went into a bathroom and emerged with a Remington 870 shotgun. Both the barrel and stock of the weapon had been shortened.
Comey said Alexis almost immediately began blazing away on the fourth floor, before going to the third floor where he repeated his actions. The building has an atrium, but, contrary to earlier reports, he was not shooting down from upper floors into the atrium.
He said Alexis went to the lobby where he shot a security guard and took his weapon, a Beretta semiautomatic pistol. He resumed moving through the building, focusing mainly on the 3rd and 4th floors, Comey said.
When Alexis ran out of ammunition for the shotgun, he started using the Beretta. He was killed by responding officers. Comey said his motive remained unknown.
A government official with knowledge of the investigation told USA TODAY that investigators from the FBI's computer forensics team were examining a computer at the Residence Inn where Alexis stayed. The official, who was not authorized to comment publicly and requested anonymity, said investigators found undisclosed "digital evidence."
WUSA-TV Washington reported that security at the scene and the response by Capitol Police has raised questions.
Anthony Meely, chairman of the Fraternal Order of Police Naval District Labor Committee, says a minimum of 11 Navy police officers were supposed to be working at the Navy Yard on Monday, but only seven were at the site. Because six had to continuing manning gates, only one could immediately respond to the attack at Building 197, Meely said.
"People died because of management rights, the right to make a decision to save money," Meely says.
"I take our response to this tragedy and our support to law enforcement partners very seriously," Capitol Chief Kim Dine said in a statement. "While I am the chief of Police, at my core I am a police officer who feels strongly about our shared commitment and responsibilities. … I place a high priority on law enforcement agency relationships and law enforcement coordination and communication."
Navy Secretary Ray Mabus ordered reviews of Alexis' four-year naval career to determine whether his conduct warranted his security clearance and fit-for-duty status. Mabus also ordered rapid assessments of the rules for when contractors are required to notify the Navy that they've reviewed an employee's clearance and of the Navy's broader security clearance system.
Building 197 remained off-limits Thursday, but employees elsewhere at the Navy Yard were reporting for work. Some said it was too soon for them to talk about the tragedy.
"It's a little surreal, I guess," Brooke Roberts, an engineer who works across the street from Building 197, told the Associated Press. "You don't think this sort of thing can happen to you at your workplace, so you're just not prepared for it."
Contributing: Russ Ptacek, Bruce Leshan and Delia Gonçalves, WUSA; Sam Fellman, Navy Times