The notoriously secretive underground marketplace Silk Road accepted online currency as payment for drugs, and police have a warrant for users' accounts.
This article titled “FBI claims largest Bitcoin seizure after arrest of alleged Silk Road founder” was written by James Ball and Charles Arthur, for theguardian.com on Wednesday 2nd October 2013 15.54 UTC
US authorities have arrested Ross William Ulbricht, 29, alleged to be the owner and operator of Silk Road, the best-known underground marketplace for the trade of illegal drugs on the internet.
The Silk Road website – run by a man using the alias “Dread Pirate Roberts” – acted as a version of eBay for drug dealing: matching buyers and sellers of different substances, allowing them to pay using a virtually untraceable online currency known as Bitcoin. Sellers then shipped the drugs using regular post or courier services.