A businessman who was one of the early investors in a failed professional football league called the Alliance of American Football pleaded guilty Monday to charges accusing him in a $600 million cryptocurrency scheme.

Reginald Fowler was charged with bank fraud, wire fraud and other offenses that prosecutors say contributed to the AAF’s quick demise in 2019.

The guilty plea in Manhattan federal court comes at a time when other fledgling leagues are making longshot bids to loosen the National Football League’s grip on pro football. In 2019, the AAF shut down after eight weeks when it ran out of money.

Fowler, 63, of Chandler, Arizona, was once known for trying to buy the NFL’s Minnesota Vikings in 2005. He ended up as a minority owner before his involvement in the team ended in 2014.

In a statement, U.S. Attorney Damian Williams said that as part of the crypto scheme, Fowler “helped process hundreds of millions of dollars of unregulated transactions on behalf of numerous cryptocurrency exchanges, skirting the anti-money laundering safeguards required of licensed institutions that ensure the U.S. financial system is not used for criminal purposes.”

Prosecutors also alleged that Fowler lied to AAF executives by claiming he controlled bank accounts with tens of millions of dollars from real estate investments and government contracts that he could use to invest in the league.

“Having accepted full responsibility in an open plea today, Reggie will have the opportunity to be heard at sentencing as to his understanding of the circumstances of the offenses and pivotal issues such as the proper amount of monetary loss attributable to Reggie,” defense attorney Edward Sapone said in a statement.