A U.S. judge ordered the release of a transcript of a voicemail from someone who tried to dissuade former National Security Adviser Michael T. Flynn from fully cooperating with Special Counsel Robert Mueller’s investigation of Russian meddling in the 2016 election.

While the identity of the caller wasn’t disclosed, Flynn told Meuller’s team he was contacted by individuals linked to the Trump administration and Congress before and after he pleaded guilty to lying to prosecutors, court records show. At least one such message was passed along to authorities. On Thursday, U.S. District Judge Emmet Sullivan ordered transcripts of the recording and Flynn’s conversations with Russian officials to be turned over no later than May 31.

The recording, when made public, could lend support to allegations in the Mueller report that President Donald Trump or his lawyers tried to obstruct the special counsel’s investigation into his 2016 campaign’s ties to Russia. After Flynn began cooperating with the Mueller, the president’s personal lawyer left a message for Flynn’s attorney reminding them of Trump’s “warm feelings” toward him, according to the Mueller report released in March.

Flynn “informed the government of multiple instances, both before and after his guilty plea, where either he or his attorneys received communications from persons connected to the administration or Congress that could have affected both his willingness to cooperate and the completeness of his cooperation,” U.S. Attorneys Brandon Van Grack and Zainab Ahmad said in a court filing unsealed Thursday.

The judge, who is handling Flynn’s sentencing, also ordered that unredacted portions of the Meuller report related to Flynn be handed over to the court by May 31.

Flynn
was to be punished a year after
pleading guilty to lying to investigators about his contacts with former Russian Ambassador to the U.S. Sergey Kislyak. But Sullivan prevailed upon the retired general to reconsider whether he wanted to proceed after the judge learned in court that Flynn had not fully discharged his obligation to cooperate with the government and would, therefore, not receive the full benefit for having done so.

Flynn, the one-time Trump administration aide, will likely testify against his former business partner, Bijan Rafkiekian, at an illegal lobbying trial set for July 15 in Alexandria, Virginia.

Mueller wrapped up his nearly two-year probe in March, concluding that there was insufficient evidence to determine Trump’s campaign had illegally collaborated with Russians who had interfered in the election. The special counsel declined to draw a conclusion on whether the president himself attempted to obstruct the investigation, deferring to Congress for further action on that issue.

Flynn’s sentencing has not yet been rescheduled.

The case is U.S. v. Flynn, 17-cr-232, U.S. District Court, District of Columbia (Washington).