The FBI has closed down Silk Road, a black market website used to buy drugs and hitmen, arresting its owner in the process.
Ross William Ulbricht, 29, is accused of "controlling and overseeing all aspects" of hidden website Silk Road, as well as plotting to kill another person who was trying to extort him.
Ulbricht, known as 'Dread Pirate Roberts' on the site, is also charged with drug trafficking, computer hacking and money laundering.
The website, dubbed the 'eBay of the drug trade', used a privacy-protecting Tor network and Bitcoin digital currency to shield the identities of buyers and sellers around the world.
In the police action, authorities seized approximately $3.6m (£2.2m) worth of Bitcoins - the largest-ever seizure of the currency.
FBI agent Christopher Tarbell said Silk Road was us
ed by "several thousand drug dealers" to sell "hundreds of kilograms of illegal drugs".
The website allowed users to anonymously browse through nearly 13,000 listings under categories such as "cannabis", ''psychedelics" and "stimulants", "erotica", "forgeries" and "fireworks" before making purchases with Bitcoins.
One listing for heroin promised buyers: "All rock, no powder, vacuum sealed and stealth shipping."
As of July, there were nearly one million registered users of the site from the UK, US, Germany, Russia and elsewhere, the court papers said.
Federal authorities shut the site down and swooped on Ulbricht on Tuesday afternoon in a branch of San Francisco's public library.
Ulbricht was online on his laptop chatting with a co-operating witness about Silk Road when FBI agents took him into custody, authorities said.
Ulbricht did not enter a plea to any of the charges when he appeared in court on Wednesday in San Francisco.
He is due back in San Francisco federal court on Friday to discuss bail and his transfer to New York, where most of the charges have been filed.