With all the drama surrounding James Comey, it’s easy to forget that the Trump administration’s troubles started with Michael Flynn. It was Flynn who lied to Vice President Mike Pence and to FBI investigators about a meeting with the Russians, and it was the former national security adviser who the president was trying to protect when he—according to Comey’s sworn testimony—asked the ex-FBI director to “see your way clear to letting this go, to letting Flynn go.” (Trump denies saying this.)

There’s every reason to believe Flynn continues to be a key figure—and perhaps the key figure—in Robert Mueller’s investigation of Russia’s election meddling, the Trump campaign’s potential collusion in such, and other crimes that may have stemmed from those affairs. On Monday, two members of the Senate Judiciary Committee posited that Flynn was already cooperating with Mueller, potentially offering testimony that could incriminate Trump.

“If you draw conclusions as a prosecutor about what we can see from the Flynn investigation, all the signals are suggesting that he’s already cooperating with the FBI and may have been for some time,” Democratic Sen. Sheldon Whitehouse told CNN’s Wolf Blitzer. Later in the evening, Sen. Richard Blumenthal agreed with that assessment. “The likelihood of his cooperation is very high,” the Connecticut Democrat told MSNBC’s Lawrence O’Donnell. “Whether he will be truthful in cooperating, whether in fact he knows enough to justify some kind of agreement with the prosecutors, I think will be told by time.”