[Candy Annie Cane]

Ooh that's a tough one? Is there no loop hole in the doctor / patient confidentiality. What he is planning to do is tantamount to at least assault if not murder so surely there must be some allowance for this in order for you to break the oath and tell the police. Although I guess he has not done anything yet an there is nothing to say he will once he is released so the police wouldn't be able to do anything anyway.