Former Trump campaign adviser Richard Gates pleaded guilty Friday afternoon as part of a deal with special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE in his investigation into Russian interference in the election.

Gates pleaded guilty to two charges brought against him by Mueller’s team in federal court in Washington, D.C.: one count of conspiracy against the United States and one count of making a false statement to the FBI agents investigating Russian interference.

As part of the plea deal, Gates has agreed to cooperate “fully, truthfully, completely, and forthrightly” with the special counsel’s office as well as other law enforcement officials, according to court documents.

He is required to turn over relevant documents, go to meeting when requested and testify when requested both before and after he is sentenced. By agreeing to "fully cooperate," additional criminal charges will not be brought against him.

According to the criminal information filed by Mueller on Friday shortly before Gates pleaded guilty, Gates lied to federal investigators about a March 2013 meeting during which former Trump campaign chairman Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE, an unnamed member of Congress, reported by the Los Angeles Times to be Rep. Dana Rohrabacher Dana Tyrone RohrabacherDemocrat Harley Rouda advances in California House primary Lawyers to seek asylum for Assange in France: report Rohrabacher tells Yahoo he discussed pardon with Assange for proof Russia didn't hack DNC email MORE (R-Calif.), and an unnamed lobbyist discussed Ukraine.

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Mueller filed the criminal information one day after he unveiled a new superseding indictment charging Gates and Manafort with a slew of financial-related crimes stemming from their work for pro-Russian political forces in Ukraine over the past decade. The alleged crimes are unrelated to the work Manafort and Gates did for the Trump campaign.

Mueller accused the two longtime business associates of laundering more than $30 million dollars in income that they hid from the U.S. government.

Speculation has mounted over the past week that Gates would plead guilty and cooperate in Mueller’s probe, making him a key witness who could testify in the criminal case against Manafort. The development is expected to ratchet up pressure on Manafort to cooperate in Mueller’s probe.

Manafort, who resigned as Trump’s campaign chairman in August 2016 after reports surfaced about his work for Russian-backed Ukrainian oligarch Viktor Yanukovych, could offer key details about the campaign relevant to Mueller’s broader inquiry into whether Trump campaign associates colluded with Moscow.

Manafort issued a statement in response to Gates's guilty plea saying he is innocent.

“Notwithstanding that Rick Gates pled today, I continue to maintain my innocence," Manafort said. "I had hoped and expected my business colleague would have had the strength to continue the battle to prove our innocence. For reasons yet to surface he chose to do otherwise. This does not alter my commitment to defend myself against the untrue piled up charges contained in the indictments against me.”

Gates served as Manafort’s deputy on the campaign and went on to work for Trump's transition team.

In a letter obtained by ABC News earlier Friday, Gates told friends and family that he had decided to plead guilty for the sake of his children.



“Despite my initial desire to vigorously defend myself, I have had a change of heart,” Gates wrote. “The reality of how long this legal process will likely take, the cost, and the circus-like atmosphere of an anticipated trial are too much. I will better serve my family moving forward by exiting this process.”

- Updated at 5:54 p.m.