The Defense Department is poised to take over background investigations for the federal government, using increased automation and high-tech analysis to tighten controls and tackle an enormous backlog of workers waiting for security clearances, according to U.S. officials.

The change aims to fix a system whose weaknesses were exposed by the case of a Navy contractor who gunned down a dozen people at Washington’s Navy Yard in 2013. He was able to maintain a security clearance despite concerns about his mental health and an arrest that investigators never reviewed.