I had one that wasnt beaten but was scared as hell. He would not come to me or would freeze up. He hunts great. I started taking him with me in the truck...inside the cab. Go through McDonalds and get a hamburger and always petting him while taking him in the truck.
It helped but wasnt what I wanted. Recently I had a female in heat and decided to tie him up by the house. HE was right next to my back door. I would see him several times a day and always feed him scraps and occassionally let him inside. The feeding scraps and always talking and petting seemed to do the best. He has changed a lot.
He cold as ice now.
I dont know if this will work on every dog but think they need lots of attention to gain the trust.