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!