Fox News’s Tucker Carlson reported exclusively on Thursday night that Robert Mueller has offered Tony Podesta, the brother of a longtime friend to Hillary Clinton, immunity to testify against his business partner, Paul Manafort.

FBI special counsel Mueller, who has been tasked with the ongoing investigation into whether Trump’s campaign associates colluded with Russian officials to steal the election from Hillary Clinton, filed a 32-count indictment against Manafort earlier this year, charging him with tax evasion, bank fraud, and failing to register as a foreign agent, among other things. Manafort, who has pled not guilty, is in jail awaiting trial.

Citing two unnamed sources, Carlson reported that Mueller had offered immunity to Podesta in exchange for his testimony against Manafort, who chaired Donald Trump’s presidential campaign for four months in 2016.

Tony Podesta, whose brother is John Podesta, a longtime friend of the Clintons, was forced to resign from his company last October when faced with criminal charges from Mueller for work his firm did for a Ukrainian nonprofit for Manafort. The Washington Examiner reports:

Manafort and Podesta’s firms worked together in a public relations campaign for the European Centre for a Modern Ukraine nonprofit, which was believed to be backed by the pro-Russian and oligarch-funded Ukrainian political group Party of Regions. Sources who spoke with NBC News in October said the Podesta Group became of significant interest because it may have violated the Foreign Agents Registration Act. FARA states Americans who lobby for foreign governments, leaders, or political parties must disclose their activities with the Justice Department.

“For a near identical crime, Bill and Hillary’s friend could escape and emerge completely unscathed while Paul Manafort may rot in jail,” Carlson said. “Only one of them made the mistake of chairing Donald Trump’s presidential campaign.”

“The F.A.R.A. law was passed back in 1938 in order to prevent the government from lobbying in the U.S.,” Carlson explained. “Over a 50 year period from 1966 to 2015, a total of only seven people were criminally charged under F.A.R.A. Many more could have been charged — Washington is brimming with unregistered foreign agents and has been for decades. And yet only seven people were charged over 50 years. In recent months, three people have been charged under F.A.R.A. What do they have in common? You guessed it — some connection to Donald Trump.”