So glad you caught the little guy. Three years ago someone dropped off two feral kittens they had found in the road. These little guys were only about three weeks old. I've had cats my whole life, including a three and a half-week old kitten I adopted from the SPCA. These two little feral cats were the most vicious animals around food that I've ever seen. I never even knew a kitten could snarl, growl and make such unearthly sounds until I brought out the milk bottles. They actually frightened me. Even now I can't give them cat nip because they revert to snarling growling critters. So, to hear that this little guy skin/gutten a chick doesn't surprise me. They have an unbelievable capacity for survivial.
Hopefully he will have a good home well away from any further chickens. Perhaps after getting a full belly he calmed down, figuring someone would feed him now. Good luck to your friend and so nice to hear she could provide a home.