It was big news when Rudy Giuliani, once hailed as America’s Mayor, was indicted last month by a district attorney in Atlanta for allegedly being part of a criminal enterprise led by Donald Trump that sought to overturn the 2020 election results. Giuliani was back in headlines this week when he lost a defamation suit filed against him by two Georgia election workers whom he had falsely accused of ballot stuffing. Giuliani’s apparent impoverishment, caused by his massive legal bills, and even his alleged drinking have been fodder for reporters. But another major Giuliani development has drawn less attention: An FBI whistleblower filed a statement asserting that Giuliani “may have been compromised” by Russian intelligence while working as a lawyer and adviser to Trump during the 2020 campaign.

That contention is among a host of explosive assertions from Johnathan Buma, an FBI agent who also says that an investigation involving Giuliani’s activities was stymied within the bureau.

In July, Buma sent the Senate Judiciary Committee a 22-page statement full of eye-popping allegations, and the document leaked and was first reported last month by Insider (after a conservative blogger had posted it online). According to Buma’s account, Giuliani was used as an asset by a Ukrainian oligarch tied to Russian intelligence and other Russian operatives for a disinformation operation that aimed to discredit Joe Biden and boost Trump in the 2020 presidential race. Moreover, Buma says he was the target of retaliation within the bureau for digging into this.

The FBI declined to comment on Buma’s claims.

Buma’s revelations may only be the start. A source familiar with his work tells Mother Jones that other potential FBI whistleblowers who participated in the investigation involving Giuliani have consulted the same lawyer as Buma and might meet with congressional investigators in coming weeks. That attorney, Scott Horton, declined to comment.

Giuliani faces a heap of legal and financial problems, including those felony charges in Georgia. He is also an uncharged co-conspirator in the federal case in which Trump was indicted for his efforts to retain power after losing the 2020 election. He has been sued by a former assistant for rape. And apparently Trump has not helped the supposedly broke Giuliani cover his legal bills, though the former president did agree to headline a fundraiser for Giuliani.

Still, Buma’s statement suggests that Giuliani has been lucky to avoid deeper trouble over his attempt during the 2020 race to deploy made-in-Ukraine disinformation to sully Joe Biden.

It is widely known that Giuliani tried mightily to unearth and disseminate dirt on Biden in Ukraine—particularly regarding the unfounded allegation that as vice president Biden squashed an investigation of Burisma, a Ukrainian energy company for which his son Hunter was a director. This smear campaign led to Trump’s first impeachment and resulted in a federal investigation into whether Giuliani violated the Foreign Agents Registration Act. Prosecutors ended that probe last year.

But Buma’s allegations that FBI and Justice Department officials blocked his efforts to investigate these Giuliani activities and the work of suspected Russian agents who may have influenced the former New York City mayor could spark a new dust-up on Capitol Hill. As Republicans keep trying to gin up a controversy over the Bidens, Burisma, and other matters, Buma’s statement reinforces the case that this supposed Biden-Ukraine scandal was egged on or orchestrated by Russian intelligence. And it contradicts the narrative pushed by Trump and his defenders that the FBI and Justice Department have been in cahoots with Democrats.

Giuliani’s role in Trump’s coup attempt and his string of public humiliations may overshadow the Ukrainian chapter in Giuliani’s downfall. But, according to Buma and various US intelligence findings, Giuliani apparently was a dupe—a useful idiot—for suspected Russian operatives and propagandists. And the bureau, Buma says, investigated this—until it didn’t.

Buma’s statement highlights Giuliani’s relationship with Pavel Fuks, a wealthy Ukrainian developer, who in 2017 hired Giuliani and paid him $300,000. Fuks once told the New York Times that he had retained Giuliani to lobby in the United States for the Ukrainian city of Kharkiv, where Fuks then lived. Giuliani has denied that he was paid to lobby for Kharkiv, insisting he only provided advice regarding security to the city. And Fuks has changed his tune. Through a spokesperson, he told Mother Jones that Giuliani’s work was limited to advising the city.

In his statement, Buma says that the FBI assessed Fuks to be a “co-opted asset” of Russian intelligence services, meaning a person who Russian intelligence used to advance its goals. Buma’s complaint does not name a specific Russian intelligence agency, but a person who spoke to agents involved in this investigation says that the FBI believes Fuks worked for the FSB, the successor to KGB. All this raises the possibility that Giuliani, a former Republican presidential candidate who became a close adviser to Trump, received a large payment directly from a Russian asset.

Buma alleges that Fuks has carried out various tasks for Russian spies, including laundering money for them. Fuks also reportedly paid locals to spray-paint swastikas around Kharkiv in the weeks before Russia’s invasion. Buma says Fuks did so to bolster Vladmir Putin’s claim that the invasion aimed to achieve the “de-Nazification of Ukraine.”

Fuks denies these claims. “Mr. Fuks has never cooperated with Russian intelligence,” his spokesperson says.

Buma maintains that his investigative work led to Customs and Border Patrol in 2017 revoking Fuks visa for travel to the United States and that the FBI assessed that Fuks constituted “a national security threat,” a finding that caused Fuks to be placed on an organized crime watch list. Buma also says that he sent the Treasury Department a recommendation that the United States sanction Fuks. To date, the US government has not done so.

Ukraine has sanctioned Fuks, and it is reportedly investigating him for fraud and tax evasion. Fuks now lives in London, according to recent media reports.

In his statement, Buma says that he developed suspicions that Giuliani, through his relationship with Fuks, was “compromised by the RIS,” meaning the Russian Intelligence Services. That is a striking claim—an allegation that Russian spies may have obtained influence over a top adviser to the US president.

It’s a new piece of information to add to a pile of public indications that Giuliani left himself wide open to manipulation by Russian agents, while he was dredging Ukraine in search of derogatory information about Hunter and Joe Biden.

Giuliani has previously asserted that his work for Fuks ended before he joined Trump’s legal team in April 2018. And Fuks’ spokesperson also says that Fuks’ dealings with Giuliani finished in 2018. But Buma suggests that Fuks may have maintained an indirect connection to Giuliani by hiring in 2019 Andriy Telizhenko, a former low-level Ukrainian diplomatic official, to mount a public relations effort for him in the United States. Buma says that a source told him that Fuks retained Telizhenko to help him “establish contacts with US politicians.” Telizhenko went on to work with Giuliani, feeding him information on the Bidens.

Telizhenko, in a recent interview with Mother Jones, maintained that his work for Fuks and his contacts with Giuliani were unrelated.

But Telizhenko’s interactions with Giuliani raise serious questions about whether this Trump adviser, wittingly or not, played. a part in a covert Russian operation to discredit Biden. In 2021, the Treasury Department sanctioned Telizhenko for promoting Russian “disinformation narratives that U.S. government officials have engaged in corrupt dealings in Ukraine.” Telizhenko denies advancing disinformation or aiding Russia. He says the sanctions resulted from an FBI informant making false claims about him.

Giuliani’s efforts in Ukraine placed him in contact with several Ukrainians since sanctioned for allegedly assisting Russian disinformation efforts. The most prominent was Andriy Derkach, the son of a former KGB officer and then a Ukrainian legislator, who supplied Giuliani with unsubstantiated information about the Bidens’ supposed activities in Ukraine. After making a trip to Ukraine in the summer of 2020, Giuliani told the Washington Post that he kept in touch with Derkach and called him “very helpful.”

Trump’s Treasury Department sanctioned Derkach in 2020, calling him an “active Russian agent for over a decade.” In March 2021, a declassified report issued by the Office of the Director of National Intelligence said that Putin in 2020 signed off on a Russian intelligence effort to use proxies to feed prominent US individuals “influence narratives” aimed at hurting Biden’s campaign and helping Trump. The report cited Derkach, asserting that Putin “had purview” over his activities. Though the report did not name him, Giuliani was obviously one of the Americans the ODNI believed had been manipulated by the Russians. Last year, federal prosecutors hit Derkach with criminal charges for his alleged attempts to evade sanctions.

In his statement, Buma says he investigated Giuliani’s use of “funds he collected from political influencers to travel and conduct a series of interviews with former Ukrainian officials”—a reference to Giuliani’s campaign to gather opposition research on the Bidens. But he adds that “Giuliani was himself never considered a subject” of that part of his probe, which focused on “foreign organized crime figures and intelligence service assets or agents who chose to deal with him.”

Giuliani has admitted to meeting Ukrainians subsequently cited by the US government as Russian operatives. But he has defended his actions by arguing he had to deal with questionable people to seek information on what he has referred to as alleged Biden crimes. (No evidence has surfaced to prove Biden acted improperly in Ukraine to help his son.)

Buma reveals in his statement that he also probed whether Russian operatives or assets were involved in a 2020 Giuliani effort to make a film about Hunter Biden’s business activities in Ukraine and elsewhere. As Mother Jones reported, the GOP activists behind this venture noted in legal documents that they were considering seeking foreign financing for the film. The anti-Biden film was to include commentary from Konstantin Kulyk, a former Ukrainian prosecutor who Treasury sanctioned in 2021 for working with Derkach to spread “fraudulent and unsubstantiated allegations” about Biden. That is, this project was to feature information from sources who the US government later deemed were connected to a disinformation campaign linked to Russian intelligence.

Giuliani played a key role in trying to line up investors for the movie. His lawyer, Robert Costello, denied that Giuliani solicited money from foreign investors. The investors Giuliani did help find were two brothers, David and Kable Munger, who own a large blueberry producing company in California and have donated generously to GOP candidates. The movie never came close to being made, and people involved in the endeavor told Mother Jones the project was disorganized and incompetently managed.

The Mungers recently sued two GOP activists involved in producing the film, Tim Yale and George Dickson, along with a company they formed. Giuliani was not named as a defendant in the suit. The Mungers say that Giuliani helped persuade them to invest $1 million by saying that they would receive a share of the film’s profits. The brothers also claim that Yale and Dickson told them the movie would be “more profitable than Michael Moore’s Fahrenheit 9/11.” Giuliani, Dickson, and Yale also said, according to the Mungers’ lawsuit, that they possessed “smoking guns” revealing Joe Biden was corrupt.

Giuliani and his colleagues possessed no such material. The Mungers allege that Dickson and Yale stole their investment. In a text message to Mother Jones, Yale insisted that the lawsuit is “total hogwash.” He declined to comment further. Dickson did not respond to requests for comment.

Giuliani, according to the lawsuit, was paid $300,000 for his participation in the film project. A lawyer and a spokesperson for Giuliani did not respond to requests for comment.

Buma’s disclosures spell new trouble for Giuliani. They further implicate him in a covert Russian operation to tilt the 2020 election toward Trump. They also raise the possibility that Giuliani was protected by FBI officials. (After the 2016 election, the Justice Department investigated whether Giuliani had improper contacts with FBI agents during that race regarding the bureau’s investigation of Hillary Clinton, and it found no evidence Giuliani had been leaked information.) Buma’s statement offers an investigative roadmap for inquiries that could soil Giuliani’s already tarnished reputation. But the down-and-out Giuliani may get lucky: With all the controversy and scandal swirling about him, there just may not be much room in the Giuliani coverage for the allegation that he was a puppet for Putin.