What did the damage look like? Where were they wounded? How tight is your coop, and was it closed up? You might want to do some research on the "pests and predators" site. There are some pretty graphic pictures that might help you to figure out who the villain is. Weasels can get through any hole larger than 1". They kill just for the fun of it and one can wipe out an entire flock in a single night. Every predator has a typical method of attack, and does damage in a different way so if you do a thread search on predators, you'll find your killer. I wish you the best of luck. You might want to set a live trap with one of your duck carcasses (or some other type of fresh meat) outside their coop. But it helps to know what your target animal is so you'll choose the right trap and the right bait.
