Bitcoin is one of the platform for criminal to raise fund or to transfer fund. But now there is a private coin that more privacy that criminal would prefer because the blockchain allow the users to track and someone manage to track down a few of the criminal activities.
Beside from raising fund and transferring fund, scam which is considered also as a crime that can be committed by anyone is also widespread in bitcoin. But more importantly, it depends on person itself if he/she wants to commit bad deed, and I hope that most of us has a good intention in using the bitcoin.