WASHINGTON (AP) — A lawyer for Michael Flynn accused federal prosecutors of misconduct on Tuesday as a judge scheduled a December sentencing hearing for President Donald Trump’s former national security adviser.

The arguments from Flynn attorney Sidney Powell were the latest in a series of aggressive attacks on the foundations of special counsel Robert Mueller’s Russia investigation. They represented yet another step in Flynn’s evolution from a model cooperator — he was the first and only White House official to cut a deal with prosecutors — to a defendant whose newly combative and unremorseful stance may cost him a chance at the probation sentence prosecutors had previously said he was entitled to.

Even as U.S. District Judge Emmet Sullivan set a Dec. 18 sentencing date, Powell made clear that she considered the case far from resolved and accused prosecutors of withholding information. Though she said she was not seeking to have Flynn’s guilty plea thrown out, she contended the “entire prosecution should be dismissed because of egregious government misconduct.”

“There is far more at stake here than sentencing,” Powell said. She later accused the government of “being too busy working on what they wanted to accomplish in convicting Mr. Flynn” to seek truth or justice.

Prosecutor Brandon Van Grack, a member of Mueller’s team, strongly denied the accusations and said the government had given Flynn’s team more than 22,000 pages of documents.

He said the information Powell was seeking either had no bearing on the case, or was material that Flynn had been made aware of before pleading guilty to lying to the FBI about his interactions with the Russian ambassador to the United States.

Asked by Sullivan if the government stands by its recommendation that Flynn should be spared prison time for his cooperation, Van Grack said the government would file new documents on that question — suggesting prosecutors may reverse course and ask for him to spend at least some time behind bars.

If the Dec. 18 sentencing date holds, it will be his second sentencing hearing on that exact date in as many years.

Flynn was supposed to be sentenced last December for lying to the FBI about his December 2016 conversations with then-Russian Ambassador Sergey Kislyak.