Alexander Vinnik, who police allege ran BTC-e and Tradehill, a pair of popular digital currency exchange services, was arrested in Greece Wednesday on charges of laundering over $4 billion for clients involved in a wide range of crimes, Reuters reports. The arrest marked the culmination of a joint investigation spearheaded by the US Department of Justice.

Prior to Vinnik’s arrest, the identities of those behind BTC-e were unknown.

Vinnik “was charged with 17 counts of money laundering and two counts of engaging unlawful monetary transactions,” according to Stan Higgins of CoinDesk.com. He faces a maximum of 55-years in prison.

Prosecutors further accuse Vinnik of a hacking attack that caused the collapse of Mt. Gox, a service similar to Vinnik’s two aforementioned operations. Following the collapse, $450 million worth of bitcoins and $27 million in cash disappeared, Reuters says. Police say Vinnick laundered the money he obtained via the attack using BTC-e and Tradehill.

Both Vinnik and BTC-e were charged with one count of with one count of operating an unlawful money services business and one count of conspiracy to commit money laundering, Higgins reports. BTC-e was fined $110 million, Vinnik $12 million. As of 1:19 Eastern, the BTC-e website is down due to “unscheduled and ongoing maintenance,” according to a tweet released by the company. The site has been non-operational since July 25, but the company said in a tweet on Wednesday that it will return to service.

Bitcoin, started in 2011, uses “military grade cryptography” similar to that used by banks and online retailers such as Amazon to maintain users’ confidentiality and financial security. Bitcoin transactions are pseudonymous, meaning they are conducted under false names, but are recorded in a “shared public ledger” called the block chain, which acts as a virtual balance sheet, keeping track of the spendable balance on bitcoin accounts known as “wallets.” Services like BTC-e are peer-to-peer platforms that facilitate the transfer of the currency.

The pseudonymity and cryptography of Bitcoin impede traditional methods of financial regulation. Regulations are in place upon the system, though, and enforcers say Vinnick neglected to follow protocols meant to prevent money laundering. Moreover, they warn that others who violate said protocols will be subject to prosecution.

“We will hold accountable foreign-located money transmitters, including virtual currency exchangers, that do business in the United States when they willfully violate U.S. AML [anti- money laundering] laws,” said Jamal El-Hindi, acting director of the Financial Crimes Enforcement Network (FinCEN), in a statement.

The indictment of Vinnik and BTC-e is the latest result of intensified cyber law enforcement efforts around the globe. Earlier this week, US and European authorities worked jointly to arrest the operator of Alphabay, a “dark web” marketplace that facilitated the transaction of illegal goods. Alphabay was the dark-web’s biggest drug exchange platform: 40,000 vendors sold narcotics like heroin and fentanyl to over 200,000 customers on the site. Alphabay users also dealt in weapons, malware software, and other contraband.

Following the shutdown, former Alphabay users began using Hansa, a similar dark web marketplace. Last Thursday, though, Dutch authorities announced that they had infiltrated the latter site in June, and had been monitoring transactions and collecting information they could use to identify and prosecute the site’s users.

In the US, authorities, on suspicion of Russia’s cyber-interference in the 2016 presidential election, are redoubling efforts to combat Russian hacking operations.

As technology evolves, crime and law enforcement will evolve with it. The eternal battle between cops and robbers is now being played out in cyberspace.

“Just as new computer technologies continue to change the way we engage each other and experience the world, so too will criminals subvert these new technologies to serve their own nefarious purposes,” says Brian Stretch, U.S. Attorney for the Northern District of California, per Reuters.