A Utah man has pleaded guilty to a drug conspiracy charge for his role in an online black market known as the Silk Road that authorities say brokered more than $1 billion in transactions.

Curtis Clark Green of Spanish Fork entered the plea Thursday in in Baltimore.

He admitted to helping operate the website, which authorities say allowed customers to anonymously browse through nearly 13,000 categories before making purchases using the electronic currency Bitcoin.

The site was shut down last month when authorities arrested Ross William Ulbricht, a San Francisco man they say was the operation's mastermind. Authorities say he hid behind the alias of "Dread Pirate Roberts," an apparent reference to the 1987 movie "The Princess Bride." Ulbricht's lawyer said this week that his client is innocent.