Weasels are in FL. When I lived there, I saw one. How large are the openings near the top. A weasel is a lot like a rat, if it can get it's head in an opening, the rest can go through. They are adept climbers and are known for eating the heads. The behavior is attributed to a opportunity kill that can be accessed later for a meal if still available. A small live trap with some of your departed's remains will have him back in within a few days in your custody.
My friend had the exact same thing happen. It turned out to be an owl, a big owl. And once with a raccoon that climbed and waited for chicken to be curious. You might want to think about a coop door.
Thank you all. Turns out it was an owl....a very large owl. It had broke through the net I had as a roof.. it was caught in the act but not before it beheaded another chick. Fixed the roof...hopefully all will be well.