A former top counterintelligence official for the FBI’s New York field office pleaded guilty on Tuesday to violating U.S. sanctions by helping a Russian oligarch dig up information on his business competitor.

Charles McGonigal, who investigated Russian oligarchs during his two-decade tenure at the FBI before retiring in 2018, struck a plea deal with prosecutors from the U.S. attorney’s office for the Southern District of New York. In federal court, he admitted to one count of conspiracy to violate the International Emergency Economic Powers Act and money laundering, according to the Justice Department.

The charge, which carries a maximum sentence of five years in prison, stemmed from a 2021 scheme to evade U.S. sanctions on behalf of Oleg Deripaska, an aluminum magnate and associate of Russian President Vladimir Putin.

McGonigal agreed to probe a rival Russian oligarch, Vladimir Potanin, to try to have him sanctioned in exchange for concealed payments from Deripaska. He also tried to get Deripaska removed from the U.S. sanctions list.

“After his tenure as a high-level FBI official who supervised and participated in investigations of Russian oligarchs, Charles McGonigal has now admitted that he agreed to evade U.S. sanctions by providing services to one of those oligarchs, Oleg Deripaska,” U.S. Attorney Damian Williams said in a statement on Tuesday.

Sentencing for the case is set for Dec. 14. McGonigal is concurrently facing a separate case involving his collection of $225,000 in undisclosed payments from a former Albanian intelligence officer while working for the bureau.