All you can do is follow the evidence. Also look for tracks in the coop, at the original site and all along the route. If no tracks, could be aerial... If dog like tracks you're looking for a fox or a coyote, maybe even a wolf. If it looks like a human hand, then you're looking for a coon.
Also look for poop along the trail. That can also help you identify the critter.
Also look for poop along the trail. That can also help you identify the critter.