Silk Road was an online market running on the Deep Web that originally opened in February of 2011 that operated as a Tor hidden service. As of July of 2013, there were 960,000 registered users. The website was commonly used for the sale of drugs, weapons, and various forms of contraband and used bitcoins in lieu of traditional credit cards in order to create anonymity for sales.
In October of 2013, Silk Road was shut down by the FBI and the founder and chief operator, Ross William Ulbricht, was arrested. He was sentenced to life in prison without possibility of parole. At the time of Silk Road's closing, Ulbricht was in possession of 144,000 BTC (which at the time was worth around 2.8 billion yen) that was confiscated by the FBI. The seized bitcoins were auctioned off in November of 2015.