The investigation on the link between the staff of then-Republican presidential candidate Donald Trump and Russian officials during the 2016 campaign just took two steps forward on Tuesday. Former National Security Adviser Michael Flynn reportedly will provide the Senate Intelligence Committee the documents it requested him, while fired FBI Director James Comey started talks with special counsel Robert Mueller.

Flynn previously said he would invoke his 5th Amendment right because he fears his testimony could be used against him. However, CNN reported that Flynn would submit by June 6 to the Committee an initial batch of documents.

The submission is his response to two subpoenas sent to Flynn’s business which cannot invoke the amendment.

Threat of jail

But Flynn is also complying with another subpoena from the same committee to submit also personal documents. However, he would submit fewer personal documents which have observers guessing what percentage of the committee’s original request Flynn would comply with.

The personal compliance could be because Richard Burr, the North Carolina senator who chairs the intelligence committee, and Virginia Sen. Mark Warner, the vice chairman, had threatened to hold Flynn in contempt of Congress is he do not turn over the documents. Other than Flynn, also under the congressional probe are Paul Manafort, the former campaign chairman, Roger Stone, a former Trump adviser, and Carter Page, an ex-foreign policy adviser.

Comey testimony

Information from Flynn is just one side of the investigation. Another aspect that could lead to the impeachment of Trump is the testimony of Comey whom the president fired for allegedly not following the billionaire’s order to drop the investigation on Flynn. USA Today reported that Comey had started preliminary discussions with Mueller on his forthcoming appearance before the Senate committee.

There is no date yet set for Comey’s testimony, although the former director previously said it would take place after Memorial Day. Mueller is not expected to block Comey from testifying, although the fired director may be required to undergo debriefing prior to his testimony.

Comey reportedly has a secret file that documented his communications with Trump.

It includes their Feb. 14 meeting when the president allegedly asked him to drop Comey’s investigation of Flynn.

Trump previously fired Flynn for not telling the truth to other administration officials about his communications with Russian ambassador to Washington, Sergey Kislyak, before the Jan. 20 inaugurations.