The United States has arrested a Russian national and founder of a cryptocurrency exchange on charges of allegedly laundering more than $700 million, the Justice Department said Wednesday.

Anatoly Legkodymov, the founder of Bitzlato, a Hong Kong-registered cryptocurrency exchange that touted its lax approach to verifying clients’ identities, was arrested in Miami late Tuesday.

According to court documents, Legkodymov knew his company was helping criminals launder money and told a staff member that his clients were «known criminals.»

While many cryptocurrency exchanges go to great lengths to verify user identities so they don’t violate financial regulations (generally known as «know your customer» or KYC laws), the Bitzlato website claimed that it only requires users to provide an email address to register.

Starting Wednesday, Bitzlato’s displayed a message that the website had been seized by a variety of international law enforcement agencies. A Telegram bot designated to help customers appeared to be down, responding to queries with «😔 Oops, sorry.»

Chainalysis, a company that investigates the criminal use of cryptocurrencies, had previously claimed that Bitzlato played a significant role in helping to launder money for Project Terricon, which raised funds to support pro-Russian groups in Ukraine using cryptocurrency in an attempt to circumvent sanctions.

Since last year, Chainalysis found that Bitzlato had laundered more than $206 million from darknet markets, $224 million from other scams, and $9 million from ransomware attacks.

The Treasury Department also declared Bitzlato a “primary money laundering concern,” an extreme measure rarely used against financial institutions.

Ari Redbord, head of legal and government affairs at cryptocurrency analysis firm TRM labs and a former senior Treasury official, said the agency reserves that designation for particularly serious money laundering.

“If the US Treasury Department designates a financial institution as a ‘Primary Money Laundering Concern,’ the goal is to isolate it,” Redbord said. “Being cut off from the US financial system, not being able to transact in US dollars, is essentially a death sentence.”