The Department of Homeland Security has started giving employees lie detector tests to find out who is leaking details about upcoming immigration raids. The polygraph tests have been taking place for about three weeks,

The Department of Homeland Security (DHS) is using polygraph tests to figure out who could be leaking information to news outlets, with some agency officials contending the disclosed information has hampered immigration enforcement efforts,

Reports of the polygraph tests being used on staff were first reported by Bloomberg in February, where Homeland Security Secretary Kristi Noem warned that they will use them to crack down on internal leaks.

The authorities that I have under the Department of Homeland Security are broad and extensive and I plan to use every single one of them to make sure that we’re following the law," Homeland Security Secretary Kristi Noem said.

Four sources say the Department of Homeland Security has begun performing polygraph tests on employees to determine who might be leaking information to the media about immigration operations. NBC News’ Jonathan Allen breaks down how the DHS is performing these tests.