Like everyone here, I am also a dog lover and would love a German Shepherd one day. Animal cruelty is so sad because the animals (Whether they are small like rats or big like horses) cant speak for them selves and they have to rely on people like you to help them.
Taking pics/vids is a great way to try and urge the police to do something about it. Here in the UK, animal cruelty is taken very seriously (We are a nation of animal lovers!) and the RSPCA simply turn up at the house and even have the power to remove the animal without notice or warning. Please keep trying... you will win eventually.
P.S Your definately not the bad guy here!