A government contractor that handles hundreds of thousands of security clearance background checks for civilian and military workers says that some workers' personal information was compromised after a recent computer breach.
The contractor, USIS, did not identify the suspected culprit but said in a statement Wednesday that the cyberattack had "the markings of a state-sponsored attack."
USIS has already been under fire in recent months for its performance in conducting background checks on National Security Agency leaker Edward Snowden and Aaron Alexis, who killed 12 people during shootings at the Navy Yard in September 2013.
Under contracts with the Office of Personnel Management, the Department of Homeland Security and other agencies, USIS conducts many of the background checks on 4.9 million federal workers with security clearances.
Explore further: NSA: Co-worker provided a digital key to Snowden (Update)