There are a lot of way for money laundering but bitcoin is the best way among all the way of money laundering and for becoming favorite of bitcoin is one of the main reason is money laundering.
That is why Bitcoin and the Crypto currency should be regulated and we should strongly to support it too. In fact there is now an International regulation for Money laundering under Financial Action Task Force (FATF) so that it could fully combat this money laundering problem in the whole world. Hopefully that this issue of Money Laundering thru Bitcoin will be eliminated as it just give bad reputation to the whole crypto currency market.