Oh, definitely sounds like raccoons...they kill for fun and bite off the heads....I have a long standing hatred of raccoons from living in the city in the midwest- they were constantly trying to get into my locked cat door enclosure in our garage. They actually were able to learn how to open the door by turning the two knobs simultaneously. I trapped dozens over about 5 years...
So here in the foothills of northern California, I lost quite a few guineas to the raccoons who apparently worked as a team to scare the birds to one side of their dog kennel coop reinforced with poultry wire and the other coon grabbed a head and bit it off. So my first incident was 8 dead guinea hens- my whole first flock....horrible. Now it has been about 18 months since I have lost any chickens or guineas at night. I put up hot wire fencing around the dog kennel coops and then I discovered NiteGuard solar predator lights and those 2 systems are working for us! Every friend I have told about these lights has been thrilled...they are on the internet, cost about $20 each and you can speak with the family (they invented these lights that flash like a predator's eye to protect their game farm bird in Minnesota). You need enough to surround your coop, placed at the eye level of your predators ( here in the foothills of Northern California my list includes coyotes, raccoons, skunks, bobcats, mountain lions and black bears). I am primarily concerned with raccoons and coyotes. I doubt any type of coop or system could save them from bobcats, mountain lions or black bears. Our vet's trail cam revealed a bobcat peeling back one corner of a dog kennel coop and going in and out till 35 chickens were taken and buried in one night for example.
One other incident we encountered- summer of 2014 the guineas began to roost about 30' up into the fairly dense oak trees. I had no chickens yet. This went on without incident for several weeks but we sleep with our sliding door open to our bedroom. One night there was a terrible guinea screaming. We jumped up, grabbed flashlights and guns and ran out onto our deck. Just as I stopped to try to locate the screaming guinea, a huge owl swooped a few feet in front of me- it had at least a 6 foot wingspan, then it's partner flew past. Horned owls. We spent the entire night picking up our guineas off the ground ( they are night blind and just cower on the ground after being knocked out of the tree) and were able to save the whole flock. Once in awhile, a naughty guinea gets into a tree and if we can't convince it with an extending pole to come down, I grab a NiteGuard light or two ( I have extra) and point them skyward under the tree of the foolish guinea. Has worked so far...we also have golden eagles (also huge nocturnal predators) so our lives revolve around getting our 6 guineas and 7 chickens to bed before sunset...( my birds now have separate coops that are connected because the guineas were not allowing the chickens to roost on the poles so they were roosting in their nest boxes and making a big poopie mess...plus my very old guinea girl has developed a strong love of fresh eggs- so the chickens don't get out of their coop till they lay their eggs now. Behavior Modification. ) This whole poultry keeping certainly does provide abundant problem solving opportunities, right? I can't believe I have allowed myself to become enslaved by a flock of birds with no brains.
Anyway, I can guarantee you will never eliminate raccoons unless you have access to a coon hound and like to hunt at night. They are very smart and dextrous and nasty and overabundant. When they see another coon in a trap, that is a learning experience. Make sure there are no sources of food (cat, dog, grain, bird feeders, citrus, even a dirty grill or the grease catching pan) and protect your poultry with 2 systems is my best advice.
FYI There is no such thing as "rehoming" a raccoon- they are so prevalent they will just starve if you drop them off elsewhere. Plus how would you like to have people dropping off their problem raccoons in your area?