A federal judge on Wednesday ordered both former national security adviser Michael Flynn and the special counsel to turn over additional investigative records describing his January 2017 interview with FBI agents — a conversation in which Flynn later admitted he lied.

In an order filed Wednesday evening, U.S. District Judge Emmet G. Sullivan demanded to see the formal FBI records and all other relevant documents detailing Flynn’s interview with the agents in 2017 and agreed to review them under seal.

The judge’s request for more information could delay Flynn’s sentencing, which had been scheduled for Tuesday. He asked for documents to be turned over by Friday at 3 p.m.

Peter Carr, a spokesman for the special counsel, declined to comment. Attorneys for Flynn also declined to comment.

The onetime national security adviser to President Trump pleaded guilty last year to lying to investigators and has been cooperating since then with special counsel Robert S. Mueller III’s investigation of Russian interference in the 2016 campaign.

Last week, Mueller told the court he was seeking no prison time for Flynn, describing him as a critical cooperating witness in the special counsel probe and other ongoing investigations.

Sullivan sought more details about Flynn’s FBI interview a day after Flynn’s attorneys in a court filing made their own case for why their client deserved no prison time, stressing that he had been “unguarded” when he spoke to FBI agents about his conversations with the Russian ambassador during the presidential transition.

The judge is well known for his concern about defendants receiving fair treatment from the government. He also issues a standard warning to prosecutors to turn over any and all information to a defendant that could be helpful in their defense, including any evidence of government misconduct.

Sullivan famously threw out a jury’s 2008 public corruption conviction of U.S. Sen. Ted Stevens after it was discovered that prosecutors and agents had hid evidence of key government witnesses giving conflicting accounts.

Flynn, who advised Trump during the campaign and transition and served very briefly as his national security adviser, admitted last year that he lied when FBI agents came to his office in the White House four days after Trump’s inauguration to ask about the nature of his conversations with then-Russian Ambassador Sergey Kislyak.

Flynn demurred about the idea of having a lawyer sit in for the session.

Flynn later admitted that he lied when he told the agents he didn’t discuss sanctions with Kislyak in their call on Dec. 29, 2016, when in fact he had. Flynn’s call with Kislyak took place the same day that President Barack Obama had announced sanctions against Russia as punishment for interfering in the 2016 election process.

FBI agents knew Flynn was lying because the call had been monitored by U.S. intelligence officials.

In a memo seeking leniency in sentencing, Flynn’s attorneys said the former Army lieutenant general’s interview with the FBI needed to be considered in context. They said that the two FBI agents did not warn Flynn he was under investigation and did not question or rebut his account of the conversation with the diplomat, but simply let him continue speaking.

They noted that one of the agents described Flynn as appearing to consider the agents “allies.”

Flynn’s attorneys stressed that he accepted responsibility for his false statement, despite later learning one of the agents who interviewed him had himself been under investigation for misconduct.