The county sheriffs and their respective deputies shall serve all subpoenas of the commission or its deputies and shall receive the same fees as are provided by law for like services. Provided, however, if the witness is in another county, the subpoena may be served by any person authorized to serve subpoenas in the county where the action originated. Each witness who appears in obedience to such subpoena of the commission shall receive for attendance the fees and mileage for witnesses in civil cases in courts of the county in which the hearing is held.