Ousted national security adviser Michael Flynn is the subject of an “open criminal investigation” stemming from his contacts with Russian officials, fired FBI director James Comey testified Thursday.

In a feverishly-anticipated hearing before the Senate Intelligence Committee, Comey confirmed under oath that Flynn was in “legal jeopardy” and that the FBI investigation of him was specifically focused on his contacts with Kremlin operatives. News articles previously reported that the FBI opened an investigation into Flynn’s work as a paid lobbyist for Turkey during the Trump administration’s transition to the White House.

Committee Chair Sen. Richard Burr (R-NC) asked Comey about an exchange he laid out in his written testimony, in which President Donald Trump asked him to “let this [investigation into Flynn] go.” The meeting happened on Feb. 14, the day after Flynn was forced to resign.

“If press accounts are right, there might have been discrepancies between facts and his FBI testimony,” Burr said, referring to an interview the FBI conducted with Flynn in late January at the White House. “In your estimation, was Gen. Flynn at that time in serious legal jeopardy and, in addition to that, do you sense that the President was trying to obstruct justice or just seek for a way for Mike Flynn to save face given he had already been fired?”

“General Flynn at that point in time was in legal jeopardy,” Comey replied. “There was an open criminal investigation in his connection with the Russian contacts and the contacts, themselves. So that was my assessment at the time.”

“I don’t think it’s for me to say whether the conversation I had with the President was an effort to obstruct,” he continued. “I took it as a very disturbing thing, very concerning, but that’s a conclusion I’m sure the special counsel will work towards to find out the intention and whether that’s an offense.”

Comey also replied affirmatively to Burr’s question about whether the special counsel “could find evidence of criminality that has not tied to the 2016 elections, possible collusion, or coordination with Russia?”

“Sure,” Comey said.

“Any complex investigation, when you turn over a rock, sometimes you find things that are unrelated to the primary investigation criminal in nature,” he added.