USA TODAY NETWORK

Sally Yates was abruptly fired as acting attorney general in the first days of the Trump administration for refusing to defend the new president’s controversial travel ban in court. However, it is the extraordinary warning she delivered just four days earlier to the White House counsel’s office about former Trump national security adviser Michael Flynn that is the reason for her testimony to Congress on Monday. You can watch the hearing live in the player above.

For the first time publicly, Yates is expected to recount to a Senate panel a Jan. 26 meeting in which she alerted White House Counsel Don McGahn that Flynn had lied to administration officials, including Vice President Mike Pence, about his conversations with Russian ambassador Sergey Kislyak before Trump's inauguration. Those misrepresentations, Yates would maintain, made the former Army lieutenant general vulnerable to possible blackmail.