You can sue your brother, the executor of your father's estate, for conversion, which is theft in a civil case and a breach of his fiduciary duty.Your remedy is to seek a constructive trust against your brother which would require him to return the stolen funds to your father's estate.  If he has used the funds for any acquisitions, a constructive trust can be used to trace the funds to those purchased items and those items or their value can be returned to your father's estate.You should also petition the court to have your brother removed as executor for breach of his fiduciary duties and a successor appointed.