Can my niece recover money stolen by an Aunt out of her dad's bank account when he passed away?

My nieces aunt took a large sum of money out of a bank account in West Virginia her dad had when he passed away (aunt's name was on the account too since he was sick), my niece's grandmother was handling probate and said that she was just going to let it go. That was six years ago. Can her case be reopened or how can she have it revisited since she is of age now?