What can I do to protect my father from my sister who has financial POA and has gone control crazy! Need some advice quickly.

My father has been placed in an assisted living facility, locked memory clinic section by my sister who holds the financial POA. She refuses to let him out of the facility and the facility will not let him out either. My father only has some short term memory loss as his only deficit. The docs think he may of had a mini stroke around the time my mother, his wife of 56 years passed from cancer. My sister was given the financial POA to assist my father during his grieving time and till he could establish a routine for maintaining their finances, investments, properties.

Having her financial POA has just exploded into a huge problem. She has placed my father in this facility and absolutely refuses to let him out. He is independent and takes care of himself. Completely ambulatory and still has a valid drivers license. He drives better then most and can still tow and manipulate their 40ft fifth wheel with ease. Anyway he owns a house in town and I, his oldest daughter live next door to him. My sister had moved her son into my dad's house and has told my dad he will not be going home. My parents own my house that is next door that I rent from them. This arrangement was done by my parents 10 years ago and they did it on their own behalf as it was a great investment, cheap. And a way to get all family members in the same city. My sister is now giving me a 60 day intent to sell notice which my father does not want at all. She had just this weekend took his drivers license. We were going to have a notary come in and verify a new POA by my dad's request but can't now that she has taken his drivers lic. Which is needed by notary for verification. Can't take him to DMV for a new one cause she will not give permission for anyone to take him from the facility. I have read a number of liteature that states that no one can keep him there and he still has rights yet I have been told by the facility and by the counties ombudsmen that if I was to take him from the facility I would be arrested! What can I do to protect my dad's rights and wishes and keep my sister from basically holding him hostage. Of course most attorneys want money up front which I do not have and my dad has been locked out of all of his! Please please help me!