The authorities identified the man as Ross Ulbricht, who was arrested by F.B.I. agents Tuesday afternoon at a library in San Francisco. Court papers filed in the case in Manhattan accuse him of engaging in a “massive money-laundering” operation and of trying to arrange a murder-for-hire. Mr. Ulbricht is to appear in federal court on Wednesday in San Francisco.

Mr. Ulbricht solicited a Silk Road user “to execute a murder-for-hire of another Silk Road user, who was threatening to release the identities of thousands of users of the site,” according to a criminal complaint unsealed Wednesday morning. Authorities also seized the Silk Road Web site.

In interviews with news reporters in the past, Mr. Ulbricht has gone by the moniker Dread Pirate Roberts, the authorities said, and until now his identity has remained a mystery.

The Silk Road marketplace is available through Tor, a popular tool for maintaining anonymity online. Bitcoin, a virtual currency, is used for transactions. The identities of sellers are not known to the buyers. About $1.2 million in sales were conducted a month in early 2012, according to a study by an assistant professor at Carnegie Mellon University, Nicolas Christin.

I only wish that it would shut down completely.

~Wald

(h/t to Matt Forney)