The founders of two cryptocurrency investment firms, one of which was, at one point, reportedly valued at $800 million before it mysteriously shut, are facing a lawsuit in a federal district court in Tennessee over allegations that include fraud and the unregistered sale of securities.

Gary Blackburn of the Blackburn Firm in Nashville, Tennessee, represents two dozen investors in the defendant investment firms, Phoenix Community Capital and its successor, Xeta Capital LLC, which were sued along with their four founders over the “tens of millions of dollars” that they allegedly fleeced from the plaintiffs.