The founder of the digital currency service Liberty Reserve has been sentenced to 20 years in prison.
Arthur Budovsky had pleaded guilty to conspiring to commit money laundering.
The online facility, shut down in 2013, had operated out of Costa Rica.
Prosecutors in New York said many of its clients had been cybercriminals who had sought to move funds anonymously.
Two other men involved in the business were sentenced to shorter jail terms.
Two more people will be sentenced on 13 May.
The authorities are still trying to locate a further two suspects.
Millions of transfers
Liberty Reserve had advertised itself as the internet's "oldest, safest and most popular payment processor... serving millions all around [the] world".
Users had to provide a name, date of birth and an email address - but prosecutors said fake credentials had been accepted.
Account holders "converted" their cash into one of the company's digital currencies, following which an "instantaneous" transfer was made and the sum converted back into real-world cash.
For this, the company charged up to $2.99 (£1.98) per transaction.
The US Justice Department said the scheme had been used to process 78 million transactions with a combined value of $8bn (£5.5bn) - many of which were related to hiding the proceeds of credit card theft, identity fraud, hack attacks and Ponzi scam investment schemes.
"Liberty Reserve founder Arthur Budovsky ran a digital currency empire built expressly to facilitate money laundering on a massive scale for criminals around the globe," said Manhattan US attorney Preet Bharara.
"Despite all his efforts to evade prosecution, including taking his operations offshore and renouncing his citizenship, Budovsky has now been held to account for his brazen violations of US criminal laws."
As part of his plea, Budovsky admitted to laundering between $250m and $550m of criminal proceeds related to US-based Liberty Reserve accounts.
In addition to the jail time, the 42 year old was also ordered to pay a $500,000 fine and forfeit $122m of company funds.