If you read the entire thread, you'll see it was a raccoon.I am interested in reading the end of this story.Is your hen still in the attack mode? Is something else killing them?
I had/have a similar problem with one of the babies I purchased in March. From 2 days old she was attacking the other babies and they were scared to death of her. She had my baby White Americana bleeding from several sores. I put her in a dog cage by herself for a few weeks and returned her to the 3 X3 puppy play pen I had the others in. She started to attack them again as soon as she was returned and I had to take her out again. ( she is a Wellsummer baby). I have had them outside for a good month now in a small baby coop which is in an inclosed 50 X 50 foot area off the main coop. ( I have them next to but not with the adults right now.) I have had my chick from hell in a dog crate in that inclosure but I do not let her in with the other babies. She will be harder to catch in that area. They are all about 3 months old and should be able to join the adults in another month. I am torn as to turn her loose with the babies or wait till I let them join the adults who will not put up with her nonsense,