Prosecutors from special counsel Robert Mueller's office said Monday that former Trump campaign chairman Paul Manafort violated his plea agreement with the government by lying to federal investigators "on a variety of subject matters".
The latest development could indicate a set back for Mueller's investigation if Manafort had not been cooperating.
As part of his plea deal, Manafort admitted to committing a host of money laundering and foreign lobbying crimes and fraud, giving the federal prosecutors leverage over him.
"A breach relieves the government of any obligations it has under the agreement, including its agreement to a reduction in the Sentencing Guidelines for acceptance of responsibility, but leaves intact all the obligations of the defendant as well as his guilty pleas", the filing reads.
The breakdown in the plea deal raises the prospect that Manafort is seeking to protect others who worked on Trump's campaign and to curry favour with the president, said former federal prosecutor David Weinstein.
Deadlocked charges from the previous trial were to be dismissed if there was "successful co-operation" with the special counsel.
CNN's Don Lemon hosted a panel discussion to explain the latest unraveling into Special Counsel Robert Mueller's investigation into the 2016 Russian Federation probe.
In August, Manafort was convicted of financial fraud relating to his work as a political consultant in Ukraine.
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Manafort denied the charges, and his attorneys in a joint filing wrote that he "has provided information to the government in an effort to live up to his cooperation obligations".
As part of his plea agreement, Manafort also agreed to forfeit five properties he owned in NY, including his apartment at Trump Tower and his sprawling estate in the Hamptons.
For more than a year now, Manafort has been at the heart of several unresolved threads of the Mueller investigation.
Prosecutors did not elaborate on areas where they contend that Manafort lied.
Manafort has been held in a detention centre in Virginia since June. Kilimnik, though also charged by Mueller, has not surfaced in the United States court system. He'll be sentenced in February in his criminal case in Virginia, which he took to trial and lost.
In September Manafort accepted the plea deal on related conspiracy charges in return for an agreement to co-operate with Mr Mueller's investigation.
The filing came after Manafort talked in detail to prosecutors before his plea, and despite numerous visits by him and his lawyers to prosecutors' offices.
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.