This looks like what happened to my chicken yesterday four of them were slaughtered while I was in the plane coming back for Massachusetts. Their heads were torn off and one of them was totally missing My coop is enclosed but then I cut a hole so that they could go out to the 15 ft run that's got a 15-ft fence I don't know if raccoons can climb or not My neighbors say yes they can I also see chicken hawks in the sky but my dog usually barks and they go away I've also had possums in there and of course the darn groundhogs eat the food. What can I kill the raccoon with I'm ready I got a gun as well and I'm not shy. My heart is broken cuz I've had them for so long they used to follow me all around the backyard Make me smile
Raccoons are very skilled at climbing, and from the pictures that does look to be what has attacked your chickens. Looking at your setup it does not look like your run is covered at the top? As you've unfortunately had to find out, predators will try to find any entry point they can, and an uncovered top is easy access for climbers and flyers. If you plan on getting more chickens again I strongly recommend covering the top with some sort of netting. I can't tell if that chain-link is the whole run or just part of it, but the holes are big enough for smaller predators to slip through, so you may want to look into predator proofing that as well.