Punish owner from Denver that left dog outside to freeze to death

Police responded to a situation involving a careless and irresponsible owner that leaves his pets outside in the cold. What's shocking, however, is that instead of placing charges the owner was simply talked into letting the pup in. If the current law states that anyone refusing to bring the pet inside can be fined up 1000$ and be incarcerated for up to a year, why are the police then refusing to enforce such standards on this owner, or the very least ban the owner from owning anymore pets?