Flynn, a former national security advisor, not only told investigators about these communications but also provided the special counsel's office with a voicemail of one instance. Prosecutors said in their filing that they were not aware of some of these attempts until Flynn informed them.

In a filing attached to his sentencing memorandum, federal prosecutors said 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 that cooperation."

A federal judge has ordered prosecutors to file transcripts of the voicemail as well as transcripts of any other recordings of Flynn, including his conversations with Russian officials. Judge Emmet Sullivan said they have until May 31 to file the transcripts, and also requested the actual audio recordings.

It appears that the Mueller report did contain a transcript of a recording Flynn provided to special counsel investigators. In the special counsel report, investigators said shortly after Flynn agreed to cooperate, he withdrew from a joint defense agreement he had with the president. Flynn's lawyer told Trump's personal lawyer that the former national security advisor would no longer be able to have confidential communications with the president. The president's lawyer then left a voicemail for Flynn's counsel which said:

"I understand your situation, but let me see if I can't state it in starker terms. ... [I]t wouldn't surprise me if you've gone on to make a deal with ... the government. ... [I]f ... there's information that implicates the President, then we've got a national security issue, ... so, you know, ... we need some kind of heads up. Um, just for the sake of protecting all our interests if we can .... [R]emember what we've always said about the ' President and his feelings toward Flynn and, that still remains ...."

Mueller's office had recommended a light sentence for Flynn, who pleaded guilty in 2017 to lying to federal investigators about conversations he had with the Russian ambassador.

Investigators said Flynn's cooperation was "particularly valuable because he was one of the few people with long-term and firsthand insight regarding events and issues under investigation by the [special counsel's office]." They also said Flynn's assistance was useful because of its timeliness, as he "began providing information not long after the government first sought his cooperation."

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