Schumer mentions Bitcoin specifically in this article: http://www.nbcnewyork.com/news/local/Schumer-Calls-on-Feds-to-Shut-Down-Online-Drug-Marketplace-123187958.html

"To make sure the money exchanged can't be traced, the site uses a new digital currency called Bitcoins that can be purchased online by visitors, according to Schumer. Using real money, users purchase these Bitcoins, which can be traded at roughly $9 to one bitcoin, and use them as proxy for real money when they buy things on Silk Road.

"It's an online form of money laundering used to disguise the source of money, and to disguise who's both selling and buying the drug," said Schumer."