Joint U.S. and Greek authorities have arrested a Russian national who is suspected of laundering more than $4 billion through a digital currency exchange that he allegedly operated.

Alexander Vinnik, 37, was indicted on Wednesday by a grand jury in the Northern District of California for operating an unlicensed money service business, money laundering, and related crimes, U.S. Attorney Brian Stretch announced. He was arrested by local Greek authorities in a small beachside village in northern Greece last Tuesday, according to Reuters.

The indictment charges Vinnik and BTC-e, the virtual currency exchange he allegedly operates, with one count of operation of an unlicensed money service business and one count of conspiracy to commit money laundering. Vinnik is also charged with 17 counts of money laundering and two counts of engaging in unlawful monetary transactions.

In a statement, Greek police claimed Vinnik laundered “at least” $4 billion in cash through BTC-e. Police said the platform saw 7 million bitcoin deposited and 5.5 million bitcoins withdrawn since it was founded in 2011.