Or set a trap with that chicken in it. I caught a possum that way inside my coop. I brought all my chickens in the house for the night. (3 chickens) they were very curious in their rabbit and dog crates!Strange, you don’t live were weasels or like animals are do you? One might have been able to sneak in and done that, though I suspect that it would have left a mess of feathers aswell. You might want to (this might sound heartless) remove the dead chicken but have it close by the coop, and set a camera up to view it. If an animal came in to try and get her they will probably come back for the body. I have a friends who has a decent sized poultry operation and that’s what she does when something kills a bird. Makes it easier to decide on what to do to protect the others