Cohen has also "voluntarily met twice" with the U.S. Attorney's Office for the Southern District of New York, the memo said, and separately "met voluntarily" with the New York Attorney General's office "concerning a state court action in which the NYAG has sued the Donald J. Trump Foundation and certain individual defendants, including Donald J. Trump".
In Friday's memo to Judge Pauley, attorneys for Cohen wrote that "Michael's decision to cooperate and take full responsibility for his own conduct well reflects his personal resolve, notwithstanding past errors, to re-point his internal compass true north toward a productive, ethical and thoroughly law abiding life".
The new charges, if any, could stem from what lawyers in Mueller's investigation say were lies told by Manafort, whom they accuse of violating a plea agreement.
In August, Cohen pleaded guilty to campaign-finance violations and financial crimes in a case brought by the US attorney in Manhattan.
In addition to his cooperation with Mueller, Cohen has also assisted in the NY state attorney general's investigation into the Trump Foundation, his lawyers revealed Friday, and has provided documents to the state attorney general in a separate, unidentified probe, too.
His lawyers note that Cohen's legal problems aren't over and he "will be named in a parallel tax case brought by New York State".
They say he'll continue to cooperate, though he wants to be sentenced as scheduled on December 12 so he can return to providing for his family. This likely indicates that they feel his cooperation is very valuable to investigators. His lawyers, though, disputed those calculations and argued his remarkable, if out-of-the-ordinary, cooperation warranted a sentence of "time-served".More news: Poroshenko Wants NATO Ships to Defend Ukraine Against Russia
"That determination has not been made yet", Prosecutor Andrew Weissmann said at a federal court hearing in Washington.
Russian spokesperson Dmitry Peskov claimed in an interview with NBC News that communication between former Trump fixer Michael Cohen and Russian officials on Trump Tower Moscow did indeed happen, but that after a few attempts at conversation it all came to nothing. "But, following the execution of search warrants in this case, almost every professional and commercial relationship that he enjoyed, and a number of long-standing friendships, have vanished".
"In the context of this raw, full-bore attack by the most powerful person in the United States, Michael, formerly a confidante and adviser to Mr. Trump, resolved to cooperate", his attorneys wrote.
The lawyers, in a document that sometimes referred to Trump as "Client-1", said Cohen committed campaign finance fraud and made false statements out of a "fierce loyalty" to Trump and at his direction. He also acknowledges he spoke to an assistant of Peskov's for 20 minutes by phone about the project.
Threaded throughout the document were testimonials from people closest to Cohen - drawn from some three dozen letters that were also submitted - depicting an image of generosity that undercuts the public perceptions of him since his guilty plea.
Prosecutors said they would relay the extent of Cohen's cooperation to the judge, as long as he keeps providing them with truthful information.
In another, a woman wrote that her husband, who is Syrian, had been friends with Cohen since 1984.