You can set a camera to see but I think it's most likely a owl. They hunt at night so maybe thats why the rooster couldn't see or attack it. Owls can actually sqeeze/flap through tiny gaps. Gaps on the roof is the number one source for owls and another reason why I think it's a owl is because owls don't eat the whole meal. They only eat the head and other small parts because they can't fly back with all the extra weight. Other times, a strong male owl can just snatch up a chicken and go to feed it's whole family. Sorry for your loss.

Could have been any animal and unless tracks were left no way to know.

Aliens

I live in Columbiana county ohio and I had 3 chickens and a rooster. Well 2 days ago I went up and one of the chickens was gone, just gone no blood no feathers no signs of a struggle. Then the next day I went up and the rooster (well what was left) was laying about 30 foot away. Another chicken was dead inside the cage. The fourth was still alive in the cage. There is a roof on top and the gap Imbetween the top of the fence and the roof was about a foot. I think it was a raccoon that killed the chickens that's body was there but I don't see why it would drag the rooster up and over the fence. It wasn't a big one about 2 pounds. The 2 bodies had the head,feet, and check eaten but everything else remained. Any ideas on what did it. Was it a raccoon, fox, or maybe a hawk or owl? Please help