Campines have very sharp and thin spurs. I've always got a few too many roosters and they often fight especially in the spring until they get the pecking order settled. That was the only time I had a fatality like that though.
I lost a hen to a huge rough legged hawk about two weeks ago. I knew it wasn't one of the usual species I see, I had to look it up in a field guide. I moved the carcass out into the middle of the field and the thing came back and fed off it for a week. Maybe some northern raptors are coming...