The founder of Bitcoin Savings & Trust is facing up to 20 years in prison after pleading guilty to one count of securities fraud on Monday.

Trendon Shavers, 33, admitted to defrauding investors after raising an estimated $4.5 million worth of bitcoins while operating BS&T, Bloomberg reported.

Shavers’ case is the first criminal securities fraud case related to digital currency in the United States.

Prosecutors said the 33-year-old Texan raised some 764,000 bitcoins from September 2011 to September 2012 after promising investors an interest rate of 7 percent a week or a total of 3,641 percent, according to the news outlet. Shavers, however, used the bitcoins to pay his earlier investors, in addition to paying for his own gambling and spa treatments in Las Vegas.