The special counsel’s office announced in a Monday court filing that it is prepared to sentence former national security adviser Michael Flynn, suggesting his months of cooperation with the federal government’s investigation has come to an end.

Flynn’s attorneys and federal prosecutors requested a sentencing date of Nov. 28 or “any of the following seven business days.”

The former Trump administration official pleaded guilty in December 2017 to lying to the FBI about his contacts with Russian officials. At the time, he said his decision to cooperate with Special Counsel Robert Mueller was “made in the best interests of my family and of our country.”

In the ensuing months, federal prosecutors and Flynn’s attorneys repeatedly filed joint requests to defer sentencing in his case, saying the matter was not “ready to be scheduled.” Frustrated by the prolonged process, U.S. District Judge Emmet Sullivan summoned the parties to a July hearing to give a fuller account of their reasoning.

Former federal prosecutors say that these repeated delays suggest that Flynn was divulging a significant amount of information useful to the government.

Flynn came under FBI scrutiny for a host of murky foreign dealings. As he admitted in court documents, Flynn failed to register as a foreign agent for a lobbying campaign he conducted on behalf of top Turkish officials.

Before his ouster from office, Flynn also reportedly convinced the National Security Council to promote his former business associates by granting them approval to build and operate dozens of nuclear power plants in the Middle East.

In interactions that cut to the heart of the special counsel probe, Flynn also admitted to acting on the orders of a “very senior member” and “senior official” of President Trump’s transition team by reaching out to senior Russian officials to discuss key foreign policy matters while President Obama was still in office. Those included two discussions with then-Russian ambassador Sergey Kislyak.