A moderator for AlphaBay — a defunct darknet site that authoritiessaid was once the world’s largest online marketplace for illegal drugs —has pleaded guilty in California to racketeering conspiracy.

Bryan Connor Herrell, 25, of Colorado, entered the plea Mondayto a charge of conspiring to engage in a racketeer-influenced corruptorganization, U.S. Attorney McGregor Scott announced in a statement. Hecould face up to 20 years in federal prison when he is sentenced in Mayin Fresno federal court.

Prosecutors said that Herrell aka Penissmith was a moderator who settled more than 20,000 disputes between sellers and buyers on AlphaBay, a gigantic global marketplace for “guns, drugs, stolen identity information, credit card numbers and other illegal items,” the stateent said.

“At the time, AlphaBay was considered to be the world’s largest online drug marketplace,” the statement said.

Herrell also was a “scam watcher” who monitored attempts to defraud AlphaBay users, authorities said.

He was paid in bitcoins, authorities said.

AlphaBay had hundreds of thousands of users before law enforcement authorities shut it down in 2017.

The man prosecutors described as its founder, Canadian citizenAlexandre Cazes, was indicted by a federal grand jury in Fresno andarrested in Bangkok. But the case was dismissed after he was foundhanged in his cell while awaiting extradition to the U.S.