What can be done to help my parents who were the target of credit card fraud by their own son?

My parents have been the target of credit card fraud by their own son. They are in their early 70's and have been receiving numerous phone calls demanding money on things they know nothing about. They have been ignoring this problem with hopes it would go away, but to no avail. They cannot stand the thought of their son going to jail and themselves being the cause, especially since they are not in the best of health...What can be done? My parents are the most lovely, caring parents a person can ask for, but they do not understand how their own son could do this and not take resposibility for his actions. My dad has always paid his bills on time and never ever overspent or had credit cards....Help, I cannot stand to see my parents having to live this way when they had tried to save for a retirement and now they have nothing.