Did you add hardware cloth to the exterior of your windows? That's the simplest way to keep windows open and raccoons out.
It's reasonably easy to do.
Cut a piece of 1/2" hardware cloth (tin or "aviation snips" work well) to 1" shorter than the height of your window TRIM and 1" shorter than...
I'm so sorry for your loss! Yes, chickens worm their way right into the heart and stay there.
Here's what I suggest you do as a way to work through grief while further improving the remaining hens' situation.
Order some hardware cloth. Amazon is by far the best deal. Search: "hardware...