One of U.S. special counsel Robert Mueller's top prosecutors will soon leave his post, a Mueller spokesman said on Thursday, confirming a move likely to add fuel to speculation that the Russia investigation is nearing a conclusion.

Andrew Weissmann, who orchestrated the prosecution of former Trump campaign chairman Paul Manafort, will leave the team "in the near future," Mueller spokesman Peter Carr said, confirming earlier media reports.

The news of his departure broke one day after Manafort was sentenced by a second judge. Manafort is facing 7½ years in prison in two cases brought by Mueller's team after being convicted of or pleading guilty to a litany of financial and other crimes.

Weissmann is in talks to take a teaching position at the New York University School of Law, according to Michael Orey, a spokesman at the university.

"Andrew has been involved with NYU Law in the past and we have been talking with him about returning to the Law School following his current commitments," Orey said.

Weissmann, who was in a Washington federal court on Thursday to attend a hearing in the special counsel's prosecution of longtime Trump adviser Roger Stone, did not respond to a request for comment.

Stone was indicted in January, accused of lying about his communications with associates about the Wikileaks website that released documents that prosecutors said were stolen by Russia and made public to hurt Trump's 2016 Democratic opponent Hillary Clinton.

Stone pleaded not guilty. His trial is set for on Nov. 5.