This is very likely, everyone will use bitcoin for money laundering. but with prices down like this, certainly they thought of canceling if saving money in bitcoin.
maybe they do this without anybody know because if they buy bitcoin with third party or not, the other people don't know where the money come from and being used for what, but if they already have bitcoin then its easy to them to sell the amount when the bitcoin price is high. i believe that there is money laundering via btc, because we can not know what kind of transaction that being used by many people in outside.