Jordan, in my experience, I would guess that a cat got it. Cats of any species usually go for the neck first to kill. Dogs do also but they drag it off to feed on it later if they can't finish it all in one meal. A racoon will kill as many as they can before feeding usually biting anywhere that they can to kill or injure the bird. According to your pictures, I would bet on a stray or ferile cat. All of the evidence points in that direction. Sorry to hear and see your loss but live traps let me know what the murderer of my birds are. They will come back. Bait the traps with cat food and shelled corn. Whatever it is, it will be back. Then you will know who did it.