The company that conducted anti-Trump research for Hillary Clinton’s 2016 campaign also worked for the Russian government, producing material that was used by Moscow to pressure the United States, according to a longtime foe of Russian President Vladimir Putin.

Businessman Bill Browder alleged Fusion GPS acted as an agent for Russian interests in 2016, when the country was trying to combat the Magnitsky Act and its sanctions on Russian officials.

Browder, 55, championed the Magnitsky Act, which was named for his tax lawyer, corruption whistleblower Sergei Magnitsky. Magnitsky died in a Russian prison in 2009 after his investigation for Browder's business uncovered hundreds of millions of dollars of Russian tax fraud implicating Russian officials.

Putin, who despises the law, retaliated by banning American adoptions of Russian children.

“The work that [Fusion GPS co-founder] Glenn Simpson did involved trying to change the narrative of how Sergei Magnitsky was killed,” said Browder. “He and the Russians paying him wanted people in Washington to believe that Sergei Magnitsky died of natural causes instead of being killed. Glenn Simpson claimed that Sergei Magnitsky wasn’t a whistleblower and that he was criminal. He also claimed that all of my testimonies to have Magnitsky sanctions imposed were untrue.”

Browder said he believes Fusion GPS's work violated the Foreign Agents Registration Act. He sent a complaint to the Department of Justice in 2016, and then-Senate Judiciary Committee Chairman Chuck Grassley urged the department to look into it in 2017.

“We did receive a response from the Justice Department, essentially stating that it can neither confirm nor deny the existence of a specific FARA investigation,” Grassley’s office told the Washington Examiner.

The DOJ declined the Washington Examiner’s request for comment, and a lawyer for Fusion GPS didn't respond, though the company has previously said "it was not required to register under FARA and it did not spread false information about William Browder or Sergei Magnitsky."

Browder pointed out that Fusion GPS and Simpson began working for Russian lawyer Natalia Veselnitskaya, who would later make headlines for her meeting with Donald Trump Jr. at Trump Tower, in 2014 and provided her with anti-Magnitsky research for years. Veselnitskaya, a former Russian prosecutor, maintained Russian government ties, according to special counsel Robert Mueller, including lobbying against 2016's expanded Magnitsky Act.

The DOJ alleged that Russia-owned real estate company Prevezon Holdings laundered fraudulent money, and the company later settled with the DOJ for $5.9 million in what the department called "a $230 million Russian tax refund fraud scheme involving corrupt Russian officials."

Veselnitskaya hired law firm BakerHostetler to help Prevezon in court, and the firm hired Fusion GPS, which Simpson confirmed in an interview with the Senate Judiciary Committee in August 2017.

"Browder was always eager to testify before Congress or appear on TV, but he did not want to answer questions from BakerHostetler lawyers about his role as a whistleblower in the Prevezon case. So the lawyers asked Fusion to figure out how they could get Browder’s testimony. What ensued was a legal game of cat and mouse in which Fusion developed information that would help BakerHostetler subpoena Browder multiple times, forcing him to testify about his business activities in Russia and earning Fusion his everlasting enmity. The U.S. government had staked its case against Prevezon on the credibility of Browder. Yet he was reluctant to explain under oath where he had obtained his evidence. It was an odd position for a human rights crusader to take," Simpson and Fusion GPS co-founder Peter Fritsch wrote in their new book, Crime in Progress: Inside the Steele Dossier and the Fusion GPS Investigation of Donald Trump.

“I participated in two all-day depositions, but the case was settled before it went to court," said Browder. "Otherwise, I would’ve been on the witness stand.”

Foreign Intelligence Surveillance Act documents released in 2018 show the DOJ and the FBI made extensive use of Steele’s dossier in 2016. Fusion GPS was hired by Clinton's campaign and the DNC through the Perkins Coie law firm. Fusion GPS then hired Steele, who allegedly reached out to Russian sources to put together his dossier. Clinton’s campaign manager Robby Mook said they received briefings from Perkins Coie about Fusion GPS's findings during the campaign.

Browder contended Fusion GPS created a dossier against him, too, by using "false information."

“Since the Russians were working so closely with Simpson on the anti-Magnitsky, anti-Bill Browder dossier, it would seem unlikely to me that the Russians wouldn’t know that there was another dossier being created," Browder said.

Mueller’s report on Russian election interference detailed the June 2016 meeting involving Donald Trump Jr., campaign chairman Paul Manafort, Trump son-in-law Jared Kushner, and various Russians, including Veselnitskaya. The meeting was pitched to Trump's campaign as an opportunity to get damaging information on Clinton, but Veselnitskaya pulled a bait-and-switch and turned it into a presentation on Russia’s desire to repeal the Magnitsky Act.

Veselnitskaya presented a short dossier echoing nearly identical Kremlin talking points that were passed to a Republican congressman by the Russia prosecutor general's office in April 2016, criticizing the Magnitsky Act and criticizing Browder as a "fugitive criminal" who was engaged in a massive fraudulent financial scheme in support of Democrats. In his Senate testimony, Simpson admitted to researching many of the allegations that appeared in Veselnitskaya's talking points. When Donald Trump Jr. asked Veselnitskaya for proof, she did not provide any, according to Mueller's report. Russian American lobbyist and former Soviet military officer Rinat Akhmetshin and the Russians then complained about U.S. sanctions and mentioned Russian adoption, and the Trump associates considered it a waste of time.

Browder believes that presentation was from Fusion GPS research, though Simpson denies any foreknowledge of the Trump Tower meeting despite seeing Veselnitskaya the day before, the day of, and the day after.

Simpson "was a person who was coordinating an advocacy campaign for Natalia Veselnitskaya, and the Trump Tower meeting seemed to be part of that advocacy campaign,” said Browder. “It seems a little odd that he would know about everything else but not that one meeting.”

Veselnitskaya attended the meeting with fellow Russian anti-Magnitsky Act advocates, including Akhmetshin. Simpson told the Senate that BakerHostetler instructed Fusion GPS to pass anti-Browder research to Akhmetshin, who lobbied Congress against the Magnitsky Act. Akhmetshin, who is in Browder’s FARA complaint, criticized Browder in congressional testimony in 2017 and filed a lawsuit against him in 2018.

In January, the DOJ unsealed an indictment against Veselnitskaya, now out of reach in Russia, alleging she’d obstructed justice during the Prevezon case through secret collaboration with Russia.

Fusion GPS's co-founders said in their book that Prevezon's court case was separate from its anti-Magnitsky Act activities.

“In early 2016, Prevezon — apart from the court case — had launched a lobbying campaign against the Global Magnitsky Act, working with Akhmetshin, in a backhanded effort to discredit Browder in the halls of Congress,” they wrote.

The firm never registered under FARA, they said, because it was not lobbying.

"Fusion had no say in the matter if Prevezon decided to take evidence from a court case and repurpose it. But all this would come back to haunt Fusion," they wrote.