A subpoena may be served by the Virgin Islands marshal and probation officer of the Superior Court, if the subpoena issues from the Office of the Attorney General, or his deputy, or the Marshal of the District Court, if the subpoena issues from the Office of the United States Attorney, or his deputy, or by any other person who is not a party and who is not less than 18 years of age. Service of a subpoena shall be made by delivering a copy thereof to the person named and by tendering to him the fee for one day's attendance and the mileage allowed by law.