In relation to a person who is in the custody of the Bureau of Prisons, or who has been committed to the custody of the Attorney General pursuant to section 4241(d), or against whom all criminal charges have been dismissed solely for reasons relating to the mental condition of the person, the Attorney General or any individual authorized by the Attorney General or the Director of the Bureau of Prisons may certify that the person is a sexually dangerous person, and transmit the certificate to the clerk of the court for the district in which the person is confined. The clerk shall send a copy of the certificate to the person, and to the attorney for the Government, and, if the person was committed pursuant to section 4241(d), to the clerk of the court that ordered the commitment. The court shall order a hearing to determine whether the person is a sexually dangerous person. A certificate filed under this subsection shall stay the release of the person pending completion of procedures contained in this section.