It could also hamper Mueller's ability to turn an insider against Trump in the investigation of Russian meddling in the 2016 election.
US President Donald Trump intensified his attacks Tuesday on the special counsel probing possible collusion between Russian Federation and his 2016 electoral campaign, after prosecutors said his former campaign chairman lied to investigators.
Trump's attorney Rudy Giuliani has signaled that the White House will claim executive privilege to prevent Mueller's final report from public release, but Cevallos said the special counsel could reveal some of his strongest evidence at Manafort's sentencing. That would likely involve Mueller offering documents and witnesses at Manafort's sentencing hearing. "Because the sentencing will be open to the public and people will be able to hear what exactly Manafort did and did not do". It indicates that not only did Manafort speak extensively with the Justice Department prosecutors for their investigation, but they also believe they were able to verify or refute information he gave them. A person close to Manafort said he had a problem with his diet in the detention center in Alexandria, Va.
Travis Gettys is an editor for Raw Story.
"He believes he has provided truthful information and does not agree with the government's characterization or that he has breached the agreement", they said in the filing.More news: Mississippi Senate candidates make final pitches
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Since pleading guilty, Manafort had met with prosecutors almost a dozen times, and though members of Mueller's team have been asking him about a wide range of topics, they're "not getting what they want", a source with knowledge of the discussions told ABC News.
"It seems to me he's angling for the pardon", said David Weinstein, a former federal prosecutor in Miami.
Manafort admitted to the two conspiracy counts in Washington in September after a jury convicted him in Virginia earlier of tax and bank fraud.
The judge in DC District Court who received the update Monday night has not yet weighed in, and a sentencing for Manafort's guilty plea has not yet been scheduled.
Monday's court filing did not go into detail about what exactly Manafort allegedly lied about, and the special counsel said it would submit a more detailed sentencing submission that "sets forth the nature of the defendant's crimes and lies, including those after signing the plea agreement" at a later date. The terms of the plea agreement waive any right to retract Manafort's guilty pleas, so he's on the hook no matter what.