"Doubt the new verdict will be any different unless there is a plea deal."
Since there is no statute of limitations for murder, I suppose they could defer her prosecution until such (unlikely) time as some doctor decides to try to let her out of the looney bin.
She avoids the possibility of murder and yet, almost certainly, stays in a mental institution for the rest of her life --- staying, as she'd have no motivation for getting out, as she'd just then get tried for murder.
Works for me.
I believe they didn't try her for all the murders at the first trial.