A Ukrainian oligarch and former associate of Paul Manafort who has been fighting extradition to the United States for five years may be back in the U.S. as soon as early July, according to a letter from his attorney to a federal judge in Chicago filed Thursday.

Dmytro Firtash was indicted in 2014 for what federal prosecutors in the Northern District of Illinois allege was his role in bribing Indian officials in order to get a lucrative mining deal to sell titanium to Boeing. He was arrested in Vienna in March 2014, released on $174 million bail, and has been contesting his extradition to the U.S. ever since.

Attorney Dan Webb, who represents Firtash, said in the letter to the judge that the Austrian Supreme Court is expected to rule at a June 25 public hearing on whether Firtash will be handed over to U.S. officials.

Webb said that his client's Austrian lawyers believe that if the Austrian Supreme Court affirms a lower appellate court’s order of extradition, Firtash could be on his way to the U.S. seven to 10 days after the June hearing.

Webb writes, "While it remains impossible to predict with certainty, Mr. Firtash’s Austrian lawyers thus believe that Mr. Firtash, under the present circumstances, could face extradition as early as the first week of July."

Webb also said that in light of these developments, he is asking that the judge in the case rule on Firtash’s motion to dismiss the indictment, which argues that federal prosecutors in Chicago lack jurisdiction over him.

Federal prosecutors said in a 2017 filing that Firtash and his co-defendant in the alleged bribery scheme, Andras Knopp, "have been identified by United States law enforcement as two upper-echelon associates of Russian organized crime."

A 2018 letter from Sen. Roger Wicker, R-Miss., to then-Attorney General Jeff Sessions alleged that Firtash had acted as a "direct agent of the Kremlin" in a scheme to skim money from natural gas transfers between the Russian firm GazProm and Ukraine. NBC News obtained the letter via Freedom of Information Act litigation.

Spokespersons and attorneys for Firtash, Webb and Lanny Davis said that the allegations in Wicker's letter were "categorically and unequivocally false."

"Every single one is a lie," Davis said. "There are no facts to support them."

In 2008, according to court records, Firtash was involved with the firm of Paul Manafort, later Donald Trump's campaign chair, in an abandoned plan to redevelop New York's Drake Hotel for $850 million. Firtash's company planned to invest more than $100 million, the records say.