My educated guess would be a possum! Here is how you find out.
1] Obtain a 55 gallon drum and a 2x6 board about 6ft long.
2] grease inside of drum with crisco, vegetable oil,etc
3]buy processed chicken. Set drum near your coop with the open side up. Set the board so the predator can climb up it to the top of the drum.IMPORTANT: Drag processed chicken around in yard near the board then drag it up the board and drop it in the drum. Your enemy will waiting for you in the morning! If you dont catch anything, you got a feral cat problem. This has worked for me for 30 plus years.