Washington Navy Yard gunman Aaron Alexis tried to buy an assault rifle at a Virginia gun store but was refused, CBS reported Wednesday.
The store wouldn't sell him an AR-15 after he test-fired it, but the reason for the refusal was unclear, CBS said.
Alexis was able to buy a shotgun at the store. The weapon is believed to be the same one used in the shooting.
As Washington police dealt with the situation at the Navy Yard, the men in charge of security on Capitol Hill reacted differently about how protect members of the House and Senate and their staffs, Roll Call reported.
Terrance Gainer, the Senate's sergeant-at-arms, locked down his half of the Capitol and Senate offices. House Sergeant-at-Arms Paul Irving did not.
About an hour after the shooting at the Navy Yard began, Gainer sent a Twitter message saying there was "no known direct threat" to the Capitol, but Capitol police were "taking extra precautions."
At 1:30 p.m., Irving sent an email to House staff saying his office was "evaluating available intelligence and evidence," but that no one at the Capitol appeared to be at risk.
Both chambers convened briefly at 2 p.m., then adjourned about 10 minutes later.
Shortly after 3 p.m., Gainer ordered a lockdown of the Senate. The lockdown was partially lifted at 4:18 p.m., which allowed people to go home but no one to enter.
While saying he respected Irving's decision not to lock down the House, Gainer said it would have been "more effective and less troublesome" if both chambers had been locked down.
The result, he said, had limited effectiveness, but "served its purpose."
Rhode Island police told the Navy a month before his murderous rampage, Alexis reported hearing voices.
Alexis, who was staying at the seaside Newport Marriott hotel Aug. 7, had called police at 6 a.m. and told officers he heard "voices talking to him through the walls, floor and ceiling," a Newport police report said.
He complained he'd changed hotels three times because he was being pursued by three people keeping him awake by sending vibrations through the walls.
He said the people were sent to harass him by a person with whom he had argued at a Virginia airport while waiting to board a flight to Rhode Island, said the report, which can be found at tinyurl.com/UPI-Newport-Police-Report.
Alexis told police he hadn't seen the people, but insisted they'd followed him. He said he had no history of mental illness and explained he was a Navy contractor.
Newport police advised him to "stay away" from the people and to notify the department if the people bothered him again.
Police then contacted the Newport Naval Station's on-duty officer to advise him of what Alexis said and asked if he was really a Navy contractor, The Providence Journal reported.
William Fitzgerald told the newspaper the next time he came across Alexis' name was Monday after the Navy Yard shooting and the dead suspect's photo was flashed on TV screens.
He said police keyed his name into the system and realized he was the same person they had interviewed nearly six weeks earlier.
The Newport incident and others point to shortcomings in a system where Alexis' behavior fell below a level that would have brought a serious response from authorities, experts and officials cited by The New York Times said.
Alexis worked on a computer project as a contractor at the Navy Yard for several days before the shooting, The Washington Post reported.
He used his secret-level clearance to gain entry to the former shipyard and ordnance plant Monday, where officials said he gunned down a dozen people before being killed by police.
He was granted secret-level security clearance in March 2008, when he was working as a full-time Navy reservist, the Pentagon said.
A Defense Department official told the Post the type of clearance Alexis had was typically good for 10 years.
Former military employees who become private-sector contractors can maintain their clearance, the official said, explaining a person can keep the clearance "in the absence of unadjudicated derogatory information."
Alexis was discharged from the Navy in January 2011 after a series of run-ins with his military superiors and police.
While investigators learned more about Alexis, President Obama ordered the White House budget office to conduct the review of policies for security clearances for contractors and employees in federal agencies.
The president told Spanish-language TV network Telemundo the nation did not have a "firm-enough background-check system."
Defense Secretary Chuck Hagel also ordered a broad review into the physical security and access to military installations worldwide.
Obama also repeated his call for Congress to enact legislation to keep guns out of the hands of criminals and those with mental illness.
"I do get concerned that this becomes a ritual that we go through every three, four months, where we have these horrific mass shootings," he told Telemundo.
Congressional leaders had no immediate response to his gun-control call.
Several senators called for a congressional investigation into the granting of security clearances to government contractors.