I agree with Lorraine, there is no way i would give the dog back, that baby deserves a better life than to sit in some creeps yard for its whole life, next time it may end up killed by a car (which i saw yesterday a sheperd mix on the street dead from someone hitting it)
and not in your yard, i would take it to adoption shelter or something.
It may sound wrong but if it were me i would simply steal the abused dog from there yard and take it to where it will be loved, fed, and sheltered from the weather.