The Senate Select Committee on Intelligence is demanding former national security adviser Michael Flynn turn over any documents related to the committee's investigation into Russian meddling in the 2016 presidential election.
Senator Richard Burr, the Republican committee chairman, and Senator Mark Warner, the Democratic vice chairman, announced on Wednesday that they had issued a subpoena to Flynn. They noted they first requested he hand over relevant documents in April but that at that time he declined to cooperate.
According to NBC, it marks the first time the committee has used its subpoena power since its 9/11 inquiry.
Questions over Flynn's ties to Russian officials and how that may have connected to his role as a top adviser to Donald Trump's campaign, and later as Trump's first national security adviser, come amid multiple investigations into whether the Trump campaign colluded with Russia to interfere in the 2016 presidential race.
Weeks before the Senate committee requested the documents, Flynn reportedly sought immunity from the FBI and members of Congress in exchange for testifying. The committee declined to make that deal, NBC News reported at the time.
Flynn's attorney had said in a statement that the retired Army lieutenant general had done nothing criminal, but he wanted assurance he would not be unfairly prosecuted.
“No reasonable person, who has the benefit of advice from counsel, would submit to questioning in such a highly politicized, witch hunt environment without assurances against unfair prosecution,” attorney Robert Kelner wrote.
Flynn resigned as national security adviser in February after news broke that he misled Vice President Mike Pence about his interactions with Russia's ambassador to the US. Since then, the House Oversight Committee has requested documents related to payments and contact between Flynn and Turkey, Russia, and Kremlin-backed media outlet RT.
The Pentagon is also investigating whether Flynn broke the law by failing to disclose payments he received from Russia.
In testimony earlier this week, former acting attorney general Sally Yates told a Senate Judiciary panel that she had warned the White House that Flynn could be blackmailed by Russia. Flynn remained on the job for another 18 days before the White House asked for his resignation.