(1) The district attorney general shall have the authority to grant transactional or use immunity to a witness if the district attorney general determines that immunity is necessary to compel testimony from the witness.
(2) The immunity shall be given to the witness in writing and shall be signed by the district attorney general.
(3) The immunity granted witnesses pursuant to Tennessee Rules of Criminal Procedure, Rule 6(j)(6) shall have no application to a grand jury convened pursuant to this part.