Louisiana Code of Civil Procedure Tit. III, Art. 1355. Service of subpoena

A. Except as provided in Paragraph B of this Article, a subpoena shall be served and a return thereon made in the same manner and with the same effect as a service of and return on a citation. When a party is summoned as a witness, service of the subpoena may be made by personal service on the witness' attorney of record.

B. Except as otherwise provided by law, when the sheriff has not made service of a subpoena within five days after its receipt or when a return has been made certifying that the sheriff has been unable to make service, any person over the age of majority, not a party and residing within the state, may make service of the subpoena in the same manner as is required by the sheriff. Proof of service by a private person shall be made by filing with the clerk of the court by which the subpoena is issued a notarized return showing the title of the action and the name of the court issuing it, the date and manner of service, and the name of the person served, signed by the person who made the service.