If shown by proof satisfactory to the state treasurer that land purchased by the petitioner in the manner set forth in section 1 was occupied by the person having the record title to the land at the time of making and recording the determination relating to the land by the state treasurer and at the time the sale was made to the petitioning purchaser, and that the purchaser never obtained possession or any beneficial use of the land and that he or she acquired no title to the land by the purchase for the reason that, on the date of the determination and the sale, the land was occupied, within the meaning of the statutes under which the sale was assumed to be made to the purchaser, or, in any case where the tax homestead deed issued by the state treasurer to this state has been held invalid by any court of competent jurisdiction in a case that was pending at the time of purchase of the land from the department of natural resources by the petitioner, the state treasurer shall cause the money paid to this state to be refunded to the purchaser, or his or her assignee, with interest on that money at 6% per annum.