The guilty plea from Curtis Clark Green, 47, comes one month after federal authorities shut down the drug-dealing website, which used tough-to-track digital currency and operated on an electronic network that allows Internet users to remain anonymous and mask their locations.
Green, whose lawyer identified him as being from Spanish Fork, Utah, declined to comment after the plea hearing. His attorney also declined comment.
The website allowed users to anonymously browse through nearly 13,000 listings under categories like "Cannabis," ''Psychedelics" and "Stimulants" before making purchases using Bitcoin, a form of online currency. The site offered various illegal services along with drugs, and as of July, had nearly 1 million registered users from around the world, according to court papers.
It was shut down when authorities arrested Ross William Ulbricht, a San Francisco man they allege masterminded the operation while hiding behind the alias of "Dread Pirate Roberts," an apparent reference to a swashbuckling character in the 1973 novel and 1987 movie "The Princess Bride."
He was arrested in a branch of San Francisco's public library, where authorities say he was online with his laptop chatting with a cooperating witness. Ulbricht, who is also accused in Maryland in a murder-for-hire plot, was ordered held after a court appearance this week in New York. His lawyer said that his client is innocent and is not the person who used the "Dread Pirate Roberts" alias.
The investigation was launched in 2011 in Baltimore, where agents from U.S. Immigration and Customs Enforcement's Homeland Security Investigations formed the "Marco Polo" task force to target Silk Road and its administrators.
William Winter, the office's special agent in charge, said in a statement that his agents will continue to pursue crimes committed by users of "networks and digital currency designed to provide anonymity."
Green, who used the aliases of "Flush" and "chronic pain," admitted in court Thursday to serving as an administrator for the website. That meant he was responsible for responding to questions and complaints from buyers and sellers, checking whether law enforcement officials were secretly poking around Silk Road and having access to the details of financial transactions conducted through the black market bazaar, authorities say.
Prosecutors say he also served as a middleman between a website vendor and an undercover agent posing as a cocaine smuggler looking to sell large quantities of the drug. The vendor and undercover Drug Enforcement Administration agent negotiated a cocaine deal for approximately $27,000, and Green agreed to have the package sent to him, authorities say.
He was arrested last January after a package of one kilogram of cocaine was delivered to his house by an undercover U.S. Postal Service inspector.
He faces up to 40 years in prison at his sentencing in February.
His court appearance followed a similar plea Wednesday from Jacob George IV, an Edgewater, Md., man who admitted selling drugs via Silk Road.