It sounds like Sarcoptic Mange:
Sarcoptic mange is the name for the skin disease caused by infection with the Sarcoptes scabei mite. The mites are microscopic and can’t be seen by the naked eye. Female Sarcoptes mites burrow under the skin and leave a trail of eggs behind. This burrowing...
After breeding season, put half a dozen of your tamest bantams in with them and let the bantams show the Shetlands that you are indeed nice to be around.
I'm guessing she's alive and well. They are highly adaptive fowl and can live close to anywhere. I agree with BullChick that she's probably enjoying herself with her wild buddies.
I don't think you need to be worried about her.
There's part of a generation amongst us that doesn't take responsibility for their own actions. Sad situation for them to be in. Personally I simply couldn't push off my own conscience of not telling the the home owner if I broke something.