La. Stat. tit. 13 § 3480
Service of citation in any case provided in R.S. 13:3479 shall be made by serving a copy of the petition and citation on the secretary of state, or his successor in office, and such service shall be sufficient service upon any such non-resident; provided that notice of such service, together with a copy of the petition and citation are forthwith sent by registered mail by the plaintiff to the defendant, or actually delivered to the defendant, and the defendant's return receipt, in case notice is sent by registered mail, or affidavit of the party delivering the petition and citation in case notice is made by actual delivery, is filed in the proceedings before judgment can be rendered against any such non-resident. The court in which the action is pending may order such continuances as may be necessary to afford the defendant reasonable opportunity to defend the action.
La. R.S. § 13:3480