I, too, am sorry for your losses, and can totally relate. I just lost one of my broilers today to a red tailed hawk. I just stepped outside and saw the hawk eating the carnage and it flew off. The head was simply bit off. I watched my tree line to see the hawk watching me and waiting for me to leave. I took the dead bird out of the yard and put it in the barn, thinking that would help the hawk lose interest. I have a fenced outdoor space for my birds adjacent to my barn - so they have access to the barn at all times, but I'm thinking about providing some other cover for them. My rooster isn't old enough to offer any protection.
I also lost one of my laying hens to a neighbor dog (a dachsund, actually). Interestingly, they never offerred to pay anything to replace her. I really think that people who have never had chickens, don't understand the cost and attachment associated with them! My other 7 hens grieved for several days - telling me over and over again, what happened! No doubt, they were very distressed.
I hope you are able to get to the bottom of your kill. It might provide some closure and allow you to try to prevent it from ever happening again!