If a person serving a sentence of imprisonment objects either in writing or through his attorney to being transferred to a suitable facility for care or treatment, an attorney for the Government, at the request of the director of the facility in which the person is imprisoned, may file a motion with the court for the district in which the facility is located for a hearing on the present mental condition of the person. The court shall grant the motion if there is reasonable cause to believe that the person may presently be suffering from a mental disease or defect for the treatment of which he is in need of custody for care or treatment in a suitable facility. A motion filed under this subsection shall stay the transfer of the person pending completion of procedures contained in this section.