U.S. Capitol Police Chief Tom Manger and House Sergeant at Arms William Walker are working to identify and root out police officers who might pose “insider threats,” they told lawmakers on Tuesday.

During a hearing before members of the House Appropriations Committee, Walker said that his office has developed an “insider threat awareness program” to identify “insider threats and employees who do lose their compass.”

“The goal is to have police officers trained as insider threat specialists so we recognize the signs and symptoms and indicators that someone’s allegiance has changed,” Walker said during the House Appropriations subcommittee hearing.