Contact John Stossel at ABC. This isn't just a story about a stolen horse, it's a story about some deep local government corruption, and he likes to do stories like that. Have you contacted your State Senator and Legislator? Governor even? Go to anyone and everyone in authority, email them, call them, let them know what happening with this. Someone somehow sometime has to do something about it. I'm glad they got the rat that stole your horse, now they have to get the other rat that has also stolen your horse. If the Sheriff is actually helping the guy hide the horse because they're friends, the Sheriff could actually end up with criminal charges, too.
I'm sorry you're having such trouble. I hope they get on the ball and get you Max back really quickly and lock up all the rats involved. Unfortunately sometimes you have to also just wait for the wheels of government to turn, which can take a while. I hope the DA gets this taken care of quickly. I know it's never quick enough for us.