AKRON, Ohio (AP) — An Ohio man has been indicted federally for a business that authorities said laundered more than $300 million in cryptocurrency used by customers to make illegal purchases from the darknet marketplace.

Larry Dean Harmon, 36, of Bath Township, was arrested Tuesday after the unsealing of an indictment handed up by a Washington, D.C., grand jury in December. FBI and IRS agents also searched Harmon’s home and offices in the Akron area and a property he leased in the Central American country of Belize on Tuesday.

Harmon operated a “mixing” or “tumbling” service from 2014 through 2017 that would collect a fee from darknet customers seeking to hide the source or ownership of cryptocurrency from the prying eyes of law enforcement, prosecutors said.

Harmon advertised those services through his company called Helix and operated a darknet search engine called Grams, prosecutors said. He is accused of partnering with the underground marketplace AlphaBay seized by authorities in 2017.

A federal magistrate on Tuesday ordered Harmon held in federal custody until he is returned to Washington for prosecution.

A message seeking comment was left Thursday with Harmon’s attorney.