(1) Subject to the provisions of sub-section (2) when a person has been ordered to be detained in a certified institution under section 6, the court which ordered the detention shall forthwith forward him to the nearest certified institution with a copy of the order of detention and the person shall thereupon be handed over to the custody of the Superintendent of the institution, who shall detain him in the institution.
(2) When any such person has been sentenced to imprisonment, the court passing the sentence of imprisonment, shall forthwith forward a warrant to a jail in which he is to be confined and shall forward him to such jail with the warrant together with a copy of the order of detention. After the sentence of imprisonment is fully executed, the officer executing it shall, if detention in a certified institution for any period remains to be undergone by such person, forward him forthwith together with the copy of the order of detention to the nearest certified institution.