The co-founder of the fraudulent OneCoin cryptocurrency, a massive pyramid scheme that amassed more than $4 billion from millions of investors worldwide, was sentenced Tuesday to 20 years in prison.

Karl Greenwood, 46, who orchestrated the multibillion-dollar multilevel marketing con, pleaded guilty in December to wire fraud and money laundering charges.

His partner, Ruja Ignatova, 43, known as the “Cryptoqueen” on the FBI’s Top 10 Most Wanted list, remains at large, the U.S. Department of Justice said.

Greenwood “operated one of the largest fraud schemes ever perpetrated,” U.S. Attorney Damian Williams said in a press release.

“We hope this lengthy sentence resonates in the financial sector and deters anyone who may be tempted to lie to investors and exploit the cryptocurrency ecosystem through fraud,” Williams said.

Greenwood’s sentence was imposed by federal Judge Edgardo Ramos in U.S. District Court in lower Manhattan.

OneCoin, which began in Bulgaria in 2014, took in more than $4 billion from at least 3.5 million people between 2014 and 2016, the DOJ said. The scheme was marketed and sold through a multilevel marketing structure, which paid commission to OneCoin members who recruited others to buy crypto packages.

Greenwood, the top distributor, received 5% of all OneCoin sales, raking in more than $300 million in total, the DOJ said.

Both Greenwood and Ignatova consistently portrayed OneCoin as being the next Bitcoin-like crypto investment opportunity. But “unlike legitimate cryptocurrencies, OneCoin had no actual value and was conceived of by Greenwood and Ignatova as a fraud from day one,” the DOJ said.

The co-founders and others lied repeatedly to their investors, including by claiming that OneCoin’s value was determined by market forces when, in reality, its price was set “arbitrarily,” authorities said.

Ignatova was charged in October 2017 on counts related to fraud and money laundering. Days after a federal warrant was issued for her arrest, Ignatova flew from Bulgaria to Athens, Greece.

She “has not been seen publicly since,” the DOJ said.

The FBI is offering a reward of up to $250,000 for information leading to Ignatova’s arrest, according to her page on the agency’s Top 10 Most Wanted Fugitives list.

Her wanted poster says that she is “believed to travel with armed guards and/or associates,” and “may have had plastic surgery or otherwise altered her appearance.”