Deripaska has been under U.S. sanctions since 2018 for reasons related to Russia’s occupation of Crimea.

Given a chance to speak, McGonigal told the judge in a voice that sometimes got shaky that he had a “deep sense of remorse and am sorry for my actions.”

“I recognize more than ever that I’ve betrayed the confidence and trust of those close to me,” he said. “For the rest of my life, I will be fighting to regain that trust.”

During his August plea to a single count of conspiring to launder money and violate the International Emergency Economic Powers Act, Deripaska told the judge he accepted over $17,000 to help Deripaska collect derogatory information about another Russian oligarch who was a business competitor.

Prosecutors say McGonigal was also trying to help Deripaska get off the sanctions list and was in negotiations along with co-conspirators to receive a fee of $650,000 to $3 million to hunt for electronic files revealing hidden assets of $500 million belonging to the oligarch’s business rival.

McGonigal, who lives in New York, was separately charged in federal court in Washington, D.C., with concealing at least $225,000 in cash he allegedly received from a former Albanian intelligence official while working for the FBI. He faces sentencing in that case on Feb. 16. Rearden ordered him to report to prison Feb. 26.

McGonigal was special agent in charge of the FBI’s counterintelligence division in New York from 2016 to 2018. He supervised investigations of Russian oligarchs, including Deripaska.

The U.S. District Court for the District of Columbia has affirmed the sanctions against Deripaska, finding there was evidence he had acted as an agent of Russian President Vladimir Putin.