What crime is committed if a friend that was keeping my horse sold it to an auction/kill buyer?

My friend volunteered to keep my horse on his property when we moved into town from the country. No boarding fee was ever discussed. We helped with chores, provided feed, and took care of the farm on multiple occasions. He got a new girlfriend in March, and for some God awful reason, they took my horse to an auction and sold her to the auction owner/kill buyer. After months of investigations, I found out she was ultimately shipped to Mexico for slaughter. I rode this horse for 20 years!!! The local police claim it is all civil(while I am pursuing a civil suit), but so many others told me that if not theft, he at least committed deprivation of property. As well as a misdemeanor for not notifying me he planned to move/sell my horse. I am really confused how so many different law enforcement officers have so many different views. Any input?? I'd rather see him charged criminally, although I have a very strong civil case against him. Any suggestions? What laws have been broken in your opinion? Thanks, Jaime