Section 120. Every order of removal of the commissioner shall be signed by him or his designee and shall be directed to the officer by whom it is to be executed. All mittimuses, processes and other official papers by which a prisoner is committed or held, or attested copies thereof, shall at the time of such removal be transferred, with the order of removal, to the institution to which the prisoner is removed, and be kept therein as if he had been originally committed thereto; but if he is returned to the place from which he was removed, they shall be returned with him.