The U.S. Securities and Exchange Commission (SEC) is suing a Philadelphia day trader, accusing him of illegally taking over more than 100 brokerage accounts and using the victims' funds to artificially inflate stock prices that he would then trade against advantageously.
The trader then used an unnamed bitcoin exchange to convert the funds from U.S. dollars to bitcoin. Those proceeds were then transferred to another individual.
"To mask his payments to the other individual as part of a profit-sharing arrangement, Willner allegedly transferred proceeds of profitable trades to a digital currency company that converts U.S. dollars to Bitcoin and then transmitted the bitcoins as payment."
https://www.sec.gov/litigation/complaints/2017/comp-pr2017-202.pdf