Recently I witnessed the aftermath of a racoon that killed several hens, one each night. Of those I saw, heads on all were attached and only one had crop consumed. Very little blood was evident. I could hear commotion as coon attacked and killed and saw coon actually consuming victims so ID not guess work.Coons would typically eat the head and crop of at least a few birds (in my experience), but it's a possibility. You could try setting a trap near your coop with a little lunch meat or even a bit of a chicken carcass in case it comes back. Might not bother with it though if it didn't eat the chickens before :/