Christopher Hamilton, a 64-year-old British man wanted in the United States on money laundering and wire fraud charges related to the fraudulent cryptocurrency OneCoin, has won his battle against extradition to the U.S., according to a ruling by London’s High Court on Thursday.

Hamilton was indicted in 2019 by a New York grand jury for his alleged participation in a $4 billion Ponzi scheme involving OneCoin that scammed approximately 3.5 million people globally.

OneCoin co-founder Karl Greenwood was sentenced to 20 years in prison in New York in September for fraud and money laundering associated with OneCoin. The other co-founder, Ruja Ignatova, also known as the “Cryptoqueen,” remains at large and is on the FBI’s 10 most-wanted list. Hamilton has previously denied any wrongdoing related to OneCoin.

Although Hamilton’s extradition to the U.S. was approved last year, his appeal of that decision was upheld by the High Court on Thursday. Judge Victoria Sharp ruled that most of Hamilton’s alleged money laundering took place in the U.K., so British authorities should investigate whether he can face criminal prosecution in Britain instead of being extradited.

The Crown Prosecution Service (CPS) had previously determined Hamilton should be tried in the U.S. rather than the U.K. The City of London Police closed its investigation of Hamilton in 2019, but Sharp said new evidence identified by U.S. prosecutors could allow British police to reopen the case against Hamilton. A CPS spokesperson said the agency is carefully reviewing the court’s judgment.