Art. 439.  Subpoena of witnesses to appear before the grand jury

Upon request of the grand jury or the district attorney, the court shall issue a subpoena for a witness to appear before the grand jury to testify when questioned by the grand jury or district attorney, or both, concerning an offense under investigation.  Upon request of the grand jury or the district attorney, the court may also issue a subpoena duces tecum.  The issuance, service, and return of a subpoena provided for in this article and the effect of the return and the enforcement of the subpoena shall be as provided in Articles 731 through 737.