Russian website The Bell, known for a generally critical stance towards President Vladimir Putin and the corruption under his rule, reported Monday that Konstantin Kozlovsky had testified to carrying out attacks at the request of state intelligence organs, notably the FSB (the KGB-successor for which Putin himself had worked in Soviet times).

The testimony is potentially explosive, as it is a first-hand account of Russian interference in the 2016 presidential election that directly contradicts Putin’s denials of any involvement. President Donald Trump had indicated after a recent meeting of the Asia-Pacific Economic Cooperation summit in Vietnam that he believed Putin’s account, rather than the reports of four U.S. intelligence agencies that came to the opposite conclusion.

Kozlovsky had been arrested earlier this year as part of a sweep by Russian authorities into a group of hackers who had stolen over $50 million from Russian bank accounts since the start of 2016 using the so-called Lurk virus. His testimony comes from an Aug. 15 court hearing on whether to extend his pre-trial detention. The website cited Kozlovsky’s own Facebook page for the written transcript, and also an audio recording of the hearing posted on Soundcloud. Fortune hasn’t verified either independently.

Kozlovsky said he reported to Dmitry Dokuchayev, a major-general in the FSB, for various tasks since 2008. In 2016, Dokuchayev had instructed him to attack the DNC’s servers for the purpose of manipulating the U.S. electoral process, Kozlovsky testified.

Dokuchayev is himself now in prison on charges of treason, accused of passing similar information to U.S. intelligence agencies. In other words, Dokuchayev appears to be one of the main sources for the information on which joint U.S. agencies, in a report released by the director of national intelligence in January, argued that the Russian state had directed a campaign designed to polarize public opinion and broadly discredit the campaign of Hillary Clinton.

It’s not clear from The Bell‘s report when Kozlovsky was detained but it can be deduced from his testimony that it was no later than June 2016. That would be around three months after Clinton’s campaign chief John Podesta had some 50,000 e-mails stolen in a phishing attack. Selected e-mails were published by Wikileaks five months later, only hours after Billy Bush’s infamous Access Hollywood tape, in which Trump bragged of using his TV fame to make sexual advances on women.

Kozlovsky isn’t the first Russian to insert himself into the drama playing out between the U.S. and Russian governments over election hacking.

In May 2017, Yevgeny Nikulin claimed to have been offered cash and U.S. citizenship by FBI agents in return for confessing to the DNC hack. Nikulin had been detained in the Czech capital of Prague at the request of the U.S. Justice Department and was subsequently indicted for hacking servers belonging to LinkedIn, Dropbox and Formspring.

At the time, Czech media reported that FBI agents had interviewed Nikulin in Prague, but had not mentioned any Clinton-related offer. Instead, they wrote, the agents had been looking for connections to Stanislav Lisov, another Russian hacker detained in Europe on unrelated charges. The FBI doesn’t comment on ongoing investigations.

The Czech Republic’s supreme court approved Nikulin’s extradition to the U.S. in November, against the wishes of Russia, where he is also wanted on a minor count of computer-assisted theft.

UPDATE: This article has been updated to include information about the Nikulin case.