How badly were the cats hurt? If they just have bite marks I would not rule out a mean wandering domestic cat. As a veterinarian, I see some pretty good bite wounds from other cats. But they are usually limited to puncture and scratches. A coyote would look more like a dog attack, with bigger punctures and maybe some skin actually pulled away from the subcutaneous layers. Could be a raccoon too. They will come in yards and try to steal food and even fight over it. I would be sure your animals are current on rabies shots and be sure and not leave any food out at night. However, it could be the feces is just incidental and it is just a cat fight.

Hope the catsare doing ok.