My dad has been diagnosed with Alzheimers and his attorney is aware of this. I just found out that he has signed over POA to his attorney. What should I do?

Contact your state Board of Bar Overseers immediately and make a complaint. They should investigate the situation on your father's behalf to make sure the POA was legally executed and valid. If they will not act quickly then you should consult with an attorney who can review the situation and determine what your options are.