La. Stat. tit. 13 § 4823
Witnesses who live in the parish or within one hundred miles of the place where the court is held, upon due notice to the opposite parties, may be summoned to appear before the special commissioner by subpoena in the usual form issued by the clerk of court requiring the attendance of the witnesses at the time and place specified. If any witness shall refuse to appear or to give evidence, he shall be deemed in contempt of court which, being certified to the clerk's office by the commissioner, an attachment may issue thereupon by order of court, in the same manner as if the contempt were for not attending, or for refusing to give any testimony in court. But nothing herein contained shall prevent the examination of witnesses viva voce when produced in open court, if the court in its discretion deems it advisable.
La. R.S. § 13:4823