If a person expressly withdraws consent to the carrying out of a forensic procedure under this Part (or if the withdrawal of such consent can reasonably be inferred from the person's conduct) before or during the carrying out of the forensic procedure--
(a) the forensic procedure is to be treated from the time of the withdrawal as a forensic procedure for which consent has been refused, and
(b) the forensic procedure is not to proceed except by order of a senior police officer under Part 4 or a Magistrate or other authorised officer under Part 5.