In Iowa, can a widow be stripped of her elective share without a prenuptial agreement?

It was a late in life wedding for both, heirs have only prenup with Dad's signature, he provided generously outside the will for already wealthy widow, widow stole estate funds by forgery, now widow is demanding huge chunk of estate against Dad's will forcing loss of family business and even photos and possessions in heirs' childhood home for Iowa "elective share"!