The cited external links should provide more depth.
With the help of at least one other person, the roommates re-sold these [stolen] high-end components to various telephony equipment suppliers nationwide, washing the checks through a series of falsified bank accounts and voice-mail business fronts.
Edit: Not necessarily their own wealth.
It seems to be that BitInstant CEO sold BTC to a known Silk Road BTC dealer, who was aware of what the BTC was being used for.
http://en.wikipedia.org/wiki/Money_laundering#The_role_of_fi...
A bank must verify a customer's identity and, if necessary, monitor transactions for suspicious activity. This is often termed as "know your customer". This means knowing the identity of the customer and understanding the kinds of transactions in which the customer is likely to engage.
http://en.wikipedia.org/wiki/Money_laundering#Preventive
These laws, contained in sections 5311 through 5332 of Title 31 of the United States Code, require financial institutions, which under the current definition include a broad array of entities, including banks, credit card companies, life insurers, money service businesses and broker-dealers in securities, to report certain transactions to the United States Treasury. Cash transactions in excess of US$10,000 must be reported on a currency transaction report (CTR), identifying the individual making the transaction as well as the source of the cash.