WASHINGTON—In a small interrogation room in Virginia with a one-way mirror, employees from across the Department of Homeland Security are being summoned and hooked up to a polygraph machine.

Federal agencies have stepped up their efforts over the past few weeks to find potential leakers, and some — like the FBI, ...

Current and former officials say the crackdown at the FBI, the Pentagon and Office of the Director of National Intelligence ...

At FBI Director Kash Patel’s direction, the bureau in recent weeks has begun administering polygraph tests to ... Houlahan of Pennsylvania said in an interview this month. In recent weeks ...