A former top Russian intelligence agent was arrested and charged with treason last year after he was discovered to be cooperating with authorities in the United States to locate a Russian hacker, according to a new report.

The bombshell report comes from TV Rain, a Russian television outlet that claims to have obtained information that allegedly provides details about the circumstances of the arrest and imprisonment of Russian Federal Security Service (FSB) agent Sergey Mikhailov.

Once the head of the FSB’s Center for Information Security, a unit of the Russian intelligence apparatus that investigates cybercrime, Mikhailov—along with his deputy agent Ruslan Stoyanov—was taken into custody in December.

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While it was widely speculated the arrests and charges of treason were made because the Russian agents were working with the U.S. Central Intelligence Agency (CIA) to provide information about Russia’s attempts to influence the 2016 U.S. presidential election, the report from TV Rain alleges the charges were for helping the CIA locate a notorious Russian hacker.

The hacker in question was Roman Seleznev, a well-known hacker who targeted credit cards and financial institutions. Seleznev is also the son of a prominent Russian lawmaker, which provided him cover for his illegal services. Seleznev was arrested in the U.S. and sentenced to 27 years in jail for causing more than $169 million in fraud losses.

According to two unnamed sources close to the investigation cited by TV Rain, Mikhailov helped provide law enforcement in the U.S. with information to track down Seleznev. His information was also reportedly vital in locating Yevgeniy Nikulin, another Russian hacker wanted for hacking large U.S. organizations.

Nikulin was arrested in the Czech Republic last year after the U.S. issued an international arrest warrant. He now faces extradition to the U.S., where he would stand trial for allegedly hacking LinkedIn, Dropbox and Formspring.

In addition to supposedly helping the CIA, Mikhailov was also reported to be a member of a Russian hacktivist group called Humpty Dumpty. The organization often stole and released embarrassing information on prominent Russian figures, including politicians.

A number of Humpty Dumpty members were arrested in 2016, including the group’s leader Vladimir Anikeyev. Anikeyev only received two years in prison for his crimes, which was a surprisingly light sentence in Russia given his activity. Some have theorized the sentence was provided in exchange for information on Mikhailov.

The arrest of Mikhailov and his deputy came at around the same time a member of the hacking investigation team at cybersecurity firm Kaspersky was arrested. The employee, Ruslan Stoyanov, was taken into custody in January and charged with treason. At the time, it was reported that Stoyanov was arrested along with a senior official of the FSB was also arrested.

Stoyanov was reportedly actively working with the FSB at the time and was reportedly arrested for making payments to foreign firms. No mention of the United States was made at the time of the arrest, though the timing and charges of treason raised suspicions.