A pair of Russians are facing charges from U.S. authorities in connection with the hack that took down the world’s leading crypto exchange, Mt. Gox, in 2011.

According to court filings in the Southern District of New York, Alexey Bilyuchenko, 43, and Aleksandr Verner, 29, were charged for conspiring to launder approximately 647,000 Bitcoins after they allegedly helped hack Mt. Gox — the world’s largest crypto exchange at the time, which ultimately failed as a result of the hack.

“Bilyuchenko, Verner and their co-conspirators allegedly used their unauthorized access to Mt. Gox’s server to fraudulently cause Bitcoin to be transferred from Mt. Gox’s wallets to Bitcoin addresses controlled by Bilyuchenko, Verner and their co-conspirators,” the U.S. Department of Justice (DoJ) alleged. It added that the accused stole the vast majority of the exchange’s client holdings and then laundered the proceeds through various other crypto exchanges.

The money laundering was allegedly facilitated by a fraudulent advertising contract with a New York–based Bitcoin brokerage service that allowed the stolen proceeds to be funnelled through offshore bank accounts and shell corporations, controlled by Bilyuchenko, Verner and their co-conspirators.

In a separate indictment filed in Northern California, Bilyuchenko was also charged with money laundering conspiracy and operating an unlicensed money services business for allegedly operating a crypto exchange, BTC-e, that was widely used in global money laundering.

According to court filings, Bilyuchenko allegedly worked with others to operate the exchange from 2011 until it was shut down by law enforcement in July 2017.

“During that time period, BTC-e was one of the world’s largest cryptocurrency exchanges and was one of the primary ways by which cyber criminals around the world transferred, laundered and stored the criminal proceeds of their illegal activities,” the DoJ said.

“This announcement marks an important milestone in two major cryptocurrency investigations,” said assistant U.S. attorney general Kenneth Polite Jr. in a release. “As alleged in the indictments, starting in 2011, Bilyuchenko and Verner stole a massive amount of cryptocurrency from Mt. Gox, contributing to the exchange’s ultimate insolvency. Armed with the ill-gotten gains from Mt. Gox, Bilyuchenko allegedly went on to help set up the notorious BTC-e virtual currency exchange, which laundered funds for cyber criminals worldwide.”