(CBS) The same company that investigated Washington Navy Yard gunman Aaron Alexis for his security clearance also did a 2011 follow-up investigation of Edward Snowden, the former National Security Agency systems analyst who leaked documents about the NSA.
The company, USIS, said in a statement Thursday it conducted Alexis' background check in 2007 for the Office of Personnel Management, but that it couldn't elaborate.
USIS was working as a contractor for the Office of Personnel Management (OPM) at the time.
Alexis' clearance enabled him to get an access card needed to get into the Navy base, The New York Times points out.
Earlier this year, reports the Reuters news agency, "USIS became the focus of congressional scrutiny" when it came to light that the company had done the most recent background investigation of Snowden.
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Reuters notes that Sen. Claire McCaskill (D, Mo.), chair of the Senate Subcommittee on Financial and Contracting Oversight, said in a statement Thursday, "From Edward Snowden to Aaron Alexis, what's emerging is a pattern of failure on the part of this company, and a failure of this entire system, that risks nothing less than our national security and the lives of Americans.
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"What's most frightening is that USIS performs a majority of background checks for our government. We clearly need a top-to-bottom overhaul of how we vet those who have access to our country's secrets and to our secure facilities."
She noted that USIS does about two-thirds of background checks done by government contractors.
"That Alexis had a 'secret' security clearance and maintained it despite several violent episodes before and after the clearance was issued has reinvigorated lawmakers' calls for a review of how security clearances are issued," Reuters observes.
USIS dominates the background check industry, taking in $195 million in government payments last year and more than $215 million this year.
USIS is under a federal investigation into possible criminal violations involving its oversight of background checks, The Associated Press reported in July.