A subpoena may be served by any person 18 or more years of age. Service of a subpoena shall be made by delivering a copy thereof to the person named together with tender of the fee allowed by law, except that if the person is a witness in a criminal action for the State or an indigent defendant, the fee shall be paid before leaving the court at the conclusion of the trial by the sheriff or, in the municipal court, by the clerk thereof.
