WASHINGTON Rick Gates, a former campaign aide to President Donald Trump , pleaded guilty to two charges and will cooperate with special counsel Robert Muellers investigation.

Gates pleaded guilty on Friday afternoon to conspiracy against the United States in connection with avoiding taxes as well as a charge of lying to the Special Counsels Office and the FBI .

Gates could be sentenced to about five years in federal prison under the sentencing guidelines, though theres the potential he could get less time.

A criminal information filed Friday indicates that Gates will admit he lied in regard to what he knew about a March 2013 discussion between a member of Congress and a lobbyist. Gates will admit he lied to the FBI when he said he was told by [former campaign chairman Paul] Manafort and a senior Company A lobbyist that there were no discussions of Ukraine at the meeting, when in fact there had been discussions about Ukraine.

Manafort issued a defiant statement on Friday in which he continued to maintain his innocence and vowed to fight on.

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, Manafort said. This does not alter my commitment to defend myself against the untrue piled up charges contained in the indictments against me.

Gates is the latest member of Trumps inner circle to cooperate with the special counsel. Michael Flynn, Trumps former national security adviser, pleaded guilty to lying to the FBI in December, signaling that he had cut a deal with Mueller. And George Papadopoulos, a former foreign policy adviser to Trump, has been cooperating with the investigation for months after he pleaded guilty to a similar charge in October.

Gates, 45, was indicted in October alongside Manafort, and he has been under house arrest ever since. Both men were indicted on charges including money laundering and violating foreign lobbying laws, and pleaded not guilty at the time.

Gates reportedly had whats known as a Queen for a Day interview, which typically allows a defendant to speak openly without facing additional charges.

Speculation grew about Gates involvement in the Mueller investigation after he added a new attorney, Tom Green, to his legal team. Green is a well-known defense lawyer known for working on plea deals and had worked on cases tied to Watergate and the Iran-Contra scandal. CNN first reported that Green was seen at Muellers offices in Washington, D.C., twice in late January, and the outlet noted that Muellers team appeared to be using a softer touch with Gates compared to Manafort.

Green has continued to visit Muellers office over the past few weeks.

Three of Gates attorneys asked to be removed from his legal team earlier this month, filing a two-page motion they said would explain their reasoning for doing so, Politico reported at the time. The document was filed under seal with the U.S. District Court for the District of Columbia.

CNN noted Gates lawyers spoke in front of a judge in two additional sealed hearings in early February.

Muellers probe has heated up in recent days. Last Friday, the Justice Department announced a slew of charges against 13 Russians and three companies , detailing a sophisticated effort to sow discord among American voters in an effort to help elect Trump.

Read the court filing on Gates below:

This post has been updated with details from Gates Friday afternoon appearance in court.