Whatever gets your chickens is the worst predator. In my case, it was a bird of prey of some sort. I am guessing Harris' hawk. I found a hawk feather in the alley, so I am hoping Louise went out with one hell of a fight.
I woke yesterday morning at 0500 to the sound of screaming chickens. I jumped out of bed, opened the door to find most of my girls cowering in fright. There were 2 standing at the fence frantically calling for their friend. I took a head count, came up 2 short. I searched and searched and finally I found one of my RIR's hidden. I pulled her out and saw she had a patch on her back where there used to be feathers. I looked for my other hen, but had to go to work, so I left and decided to ride down the alley behind my house. About a 1/2 block away, I found a very large pile of Barred Rock feathers. RIP Louise...my favorite hen.