If they saw him during the night, going back to his own property, then they must have some idea where he lives! I don't see why the police or the rescuers can't go knock on his door, and talk to him about this.
Perhaps he hates cats. But this is an animal welfare situation. The cat won't live too long without water at least.
Perhaps he hates cats. But this is an animal welfare situation. The cat won't live too long without water at least.