A person finding estray sheep or goats shall immediately report them to an inspector or the director and deliver them to an inspector upon demand. If the mark or brand on the sheep or goat is recorded in the board office, the director shall notify the owner of record and make arrangements to deliver the sheep or goats to the owner of record if he is the actual owner. If the owner of record no longer owns the sheep or goats, the director shall deliver them to the subsequent purchaser who can prove ownership with a valid bill of sale. In either case, delivery shall be conditioned upon payment by the claimant of all costs incurred in keeping the sheep or goats and such other expenses as may have been necessarily incurred. If the owner cannot be ascertained after diligent inquiry, the director shall order an inspector to sell them to the person paying the highest cash price for them after giving general or special notice or advertising as the director deems necessary under the circumstances. The money arising from the sale shall be used first to defray the costs and expenses in keeping and advertising the sheep or goats and those incurred in the sale. The residue, if any, shall be placed in the board fund; provided, however, that if at any time within two years after the sale any person shall prove ownership of the sheep or goats at the time they became lost, the residue shall be paid to him.