Rights Of a POA?

My nephew has DPOA for my father. Can my nephew sell his own house and make my father's house his own permanent home? My nephew is closing bank accounts left and right. My nephew's wife is signing back of checks to be deposited and signing checks to pay bills. She is a teacher and says that they, the law won't question it at all because I am a teacher and teachers don't lie. (That is how my nephew got DPOA thru the courts, because his wife is a teacher.) They both have criminal records, one assaulted a police officer and one for obstructing a police officer and disorderly person (maybe drunk). Before my mother died my father/mother had a will/trust and I the daughter was in charge. I even paid their bills even after her death. My dad has dementia and did a new will/trust and made my nephew POA. Is this legal or not? Can my nephew have a DPOA with a record, or sell his own house?