So many likely varmints from Yotes to Hawks and all sizes in between.
After they are dead and laying there most anything will go for them- not necessarily the initial culprit.
My next door neighbor has the issue constantly. Most chickens don't last too many nights out straying.
Last summer two Bantees disappeared for a few Summer weeks- dead??? nope, they came back in early Fall- seems they roosted every night unlike some that just sit on the ground.
Good luck Clint.