Chirley, I am so sorry you and your dad are facing this situation. I had some similar issues trying to get my mom (who lived by herself) to be evaluated medically and psychologically. The hook for me was my mother's deteriorating strength which gave me and my sisters some leverage. In the end, I took her to a geriatric clinic, which provided evaluations by a medical doctor, a social worker, a psychologist and a pharmacist. I bought books on Eldercare, and talked to several medical social workers for advice. Every situation is different, but these professionals have seen most of them. My mom was not abusive, but incredibly stubborn and resistant to any kind of help.
I'm taking the liberty of attaching a link for you. I heard this program a couple of years ago. The books mentioned sound like they might be very helpful as well.
http://www.npr.org/templates/story/s...ryId=129106620