(The Center Square) – A former top FBI agent was sentenced to more than four years in prison for helping a Russian oligarch avoid U.S. sanctions.

Charles McGonigal, 55, the former Special Agent in Charge of the FBI Counterintelligence Division in New York was sentenced to 50 months in prison. He was also ordered to pay a $40,000 fine for conspiring to violate the International Emergency Economic Powers Act and to launder money in connection with his 2021 deal to provide services to sanctioned Russian oligarch Oleg Deripaska. He had faced up to five years in prison. McGonigal's defense had asked for no prison time.

McGonigal, 55, of New York, pleaded guilty in August.

"Charles McGonigal helped advance the interests of a sanctioned Russian oligarch, breaking his oath to safeguard our nation and uphold its laws," Assistant Attorney General Matthew Olsen of the Justice Department’s National Security Division said in a statement. "Today’s sentence holds him accountable for this betrayal and demonstrates this department's commitment to deny designated individuals the means to circumvent U.S. sanctions."

The U.S. Department of the Treasury's Office of Foreign Assets Control sanctioned Deripaska in 2018 was sanctioned for having worked on behalf of a senior official of the Government of the Russian Federation and for operating in the energy sector of the Russian Federation economy.

During his time at the FBI, McGonigal helped investigate Deripaska and other Russian oligarchs. As a Special Agent in Charge, he oversaw investigations into sanctions violations. Prosecutors alleged that at the same time, he began building a relationship with an agent of Deripaska, in the hopes of doing business with Deripaska after he retired from the FBI.

In 2021, McGonigal agreed to provide services to Deripaska, in violation of U.S. sanctions. After negotiations with Deripaska's agent, McGonigal investigated a rival Russian oligarch in return for secret payments from Deripaska. While helping Deripaska, McGonigal and the agent attempted to hide Deripaska's involvement by using shell companies, forged signatures on contracts, and using the same shell companies to send and receive payment from Deripaska.

FBI agents from the same division McGonigal used to lead caught him, according to the U.S. Department of Justice.

"Charles McGonigal violated the trust his country placed in him by using his high-level position at the FBI to prepare for his future in business," U.S. Attorney Damian Williams for the Southern District of New York said in a statement. "Once he left public service, he jeopardized our national security by providing services to Oleg Deripaska, a Russian tycoon who acts as Vladimir Putin's agent. Today's sentence is a reminder that anyone who violates United States sanctions – particularly those in whom this country has placed its trust – will pay a heavy penalty."