Senators in the United States have said the government's security clearance process is "shocking" after it emerged police records on the accused Navy Yard shooter were not consulted before giving him clearance.
Aaron Alexis was a contract employee for the Defense Department.
He received a "secret" clearance in 2008 despite violent incidents in the past, including a 2004 arrest in Seattle for shooting out a car's tires.
A "secret" clearance is a mid-level security classification that allows the holder access to information considered secret and that could be damaging to national security if released.
It falls below the "top-secret" clearance, which requires more frequent background examinations.
In a hearing of the Senate Homeland Security Committee, senators asked administration officials to explain how "secret-level" clearances could be given without having to check police records even if the applicant for clearance had an arrest history.
They asked Elaine Kaplan, acting director of the Office of Personnel Management for an explanation regarding Alexis, who went on a shooting rampage and killed 12 people plus himself at Washington's Navy Yard last month.
Ms Kaplan said when the background check of Alexis was done in 2007, investigators discovered that he had been arrested.
But they did not check directly with Seattle police to obtain the arrest warrant, looking only into a Washington state database of court records to discover that the charges for "malicious mischief" had been dropped.
As a result, investigators did not learn that Alexis had shot out a car's tyres in anger.
"I find it actually incredibly shocking that we wouldn't pursue a police report in any of these arrest situations, because the nature of the charge, looking at the underlying police report, having been a prosecutor, can tell us very different information," said Republican Senator Kelly Ayotte.
Ms Kaplan said the OPM had followed all required protocols and had met investigative standards.
Committee Chairman Tom Carper said while the committee had long urged the administration to cut its backlog of security clearance applications, investigators must not sacrifice quality for speed.
"Many national security experts have long argued the security clearance process is antiquated and in need of modernisation," Mr Carper said.
"And given recent events, I think we have to ask whether the system is fundamentally flawed."
