CNN— The former head of counterintelligence for the FBI’s New York field office was charged in two separate indictments Monday for allegedly working with a sanctioned Russian oligarch after he retired and concealing hundreds of thousands of dollars he received from a former employee of an Albanian intelligence agency while he was a top official at the bureau.

Charles McGonigal, a 22-year veteran of the FBI until he retired in 2018, was arrested Saturday at John F. Kennedy International Airport Saturday when returning from international travel, a source familiar with the arrest tells CNN.

The charges, announced by the US attorney’s offices in the Southern District of New York and Washington, DC, mark a dramatic fall for McGonigal. He is expected to appear in federal court in Manhattan later Monday. His attorney said he will plead not guilty to the charges. His arraignment on the DC charges has not yet been scheduled.

McGonigal is facing charges in New York for violating US sanctions, conspiracy, and money laundering charges for working in 2021 with Oleg Deripaska, a Russian oligarch who was sanctioned for interfering in the 2016 US presidential election. Prosecutors allege McGonigal and Sergey Shestakov, a former Russian diplomat who has most recently worked as an interpreter in New York federal courts in Manhattan and Brooklyn, violated US sanctions by digging up dirt on Deripaska’s rival at the time he was already sanctioned.

In Washington, McGonigal is charged with concealing connections he had with the person who decades earlier worked for an Albanian intelligence agency, including receiving $225,000 in payments.

Prosecutors allege McGonigal, as an employee of the FBI, was required to disclose overseas travel and contacts with foreign national, which he failed to do.

During several trips overseas to Albania, Austria, and Germany, prosecutors allege McGonigal failed to disclose on US government forms that he met with the prime minister of Albania, a Kosovar politician and others.

Prosecutors allege in one meeting McGonigal urged the prime minister of Albania to be “careful about awarding oil field drilling licenses in Albania to Russian front companies.” The former employee of Albanian intelligence who paid him $225,000 had a financial interest in the government’s decision about the contracts.

One of the cash payments – $80,000 – was allegedly given to McGonigal while he sat in a parked car outside of a restaurant in New York City.

Under McGonigal’s direction, the FBI opened an investigation into a US citizen’s foreign lobbying effort based on information he received from the former employee of Albanian intelligence, according to the indictment. McGonigal never disclosed his financial relationship.

The charges out of New York allege that McGonigal first met the Russian interpreter, Shestakov, in 2018 while at the FBI through a Russian intelligence officer, known to be a diplomat previously for the Ministry of Foreign Affairs for the Soviet Union and Russian Federation.

After he retired from the FBI in 2018, McGonigal was brought on as a consultant for a New York law firm working on Deripaska’s sanctions, the court filing says.

McGonigal traveled to London and Vienna around 2019 to meet with Deripaska and others about getting the Russian oligarch “delisted” from the US sanctions list.

In 2021, they allegedly removed the law firm from the picture and McGonigal and Shestakov worked directly for Deripaska.

The former FBI agent and Shestakov attempted to hide their involvement with Deripaska, using shell companies and forged signatures to receive payments from the Russian oligarch.

In 2021, McGonigal was allegedly working to obtain “dark web” files for Deripaska that he said could reveal “hidden assets valued at more than 500 million us $” and other information that McGonigal believed would be valuable to Deripaska.

That effort that was abruptly halted when the FBI seized their personal electronic devices in November of that year.

Shestakov faces one count of false statements for attempting to hide his relationship to the former FBI agent during an interview with FBI agents after the search warrant was executed.

Deripaska, an ally of Putin, was sanctioned by the US in 2018 in response to Russian interference in the 2016 election and was charged with violating US sanctions in September.

He is one of the most well-known oligarchs in Russia and, and his name came up during the Trump-Russia investigation. He was mentioned dozens of times in special counsel Robert Mueller’s report, which says he is “closely aligned” with Putin.