63 STAT.] 81ST CONG.. 1ST SESS.-CH. 535-SEPT. 7 , 1949 ceeding. A finding by the judge that the accused is mentally compe- tent to stand trial shall in no way prejudice the accused in a plea of insanity as a defense to the crime charged; such finding shall not be introduced in evidence on that issue nor otherwise be brought to the notice of the jury. "§ 4245. Mental incompetency undisclosed at trial. "Whenever the Director of the Bureau of Prisons shall certify that a person convicted of an offense against the United States has been examined by the board of examiners referred to in title 18, United States Code, section 4241, and that there is probable cause to believe that such person was mentally incompetent at the time of his trial, provided the issue of mental competency was not raised and determined before or during said trial, the Attorney General shall transmit the report of the board of examiners and the certificate of the Director of the Bureau of Prisons to the clerk of the district court wherein the conviction was had. Whereupon the court shall hold a hearing to determine the mental competency of the accused in accordance with the provisions of section 4244 above, and with all the powers therein granted. In such hearing the certificate of the Director of the Bureau of Prisons shall be prima facie evidence of the facts and conclusions certified therein. If the court shall find that the accused was mentally incompetent at the time of his trial, the court shall vacate the judg- ment of conviction and grant a new trial. "§ 4246. Procedure upon finding of mental incompetency. "Whenever the trial court shall determine in accordance with sec- tions 4244 and 4245 of this title that an accused is or was mentally incompetent, the court may commit the accused to the custody of the Attorney General or his authorized representative, until the accused shall be mentally competent to stand trial or until the pending charges against him are disposed of according to law. And if the court after hearing as provided in the preceding sections 4244 and 4245 shall determine that the conditions specified in the following section 4247 exist, the commitment shall be governed by section 4248 as herein provided. "§ 4247. Alternate procedure on expiration of sentence. "Whenever the Director of the Bureau of Prisons shall certify that a prisoner whose sentence is about to expire has been examined by the board of examiners referred to in title 18, United States Code, section 4241, and that in the judgment of the Director and the board of examiners the prisoner is insane or mentally incompetent, and that if released he will probably endanger the safety of the officers, the property, or other interests of the United States, and that suitable arrangements for the custody and care of the prisoner are not other- wise available, the Attorney General shall transmit the certificate to the clerk of the court for the district in which the prisoner is confined. Whereupon the court shall cause the prisoner to be examined by a qualified psychiatrist designated by the court and one selected by the prisoner, and shall, after notice, hold a hearing to determine whether the conditions specified above exist. At such hearing the designated psychiatrist or psychiatrists shall submit his or their reports, and the report of the board of examiners and other institutional records relating to the prisoner's mental condition shall be admissible in evidence. All of the psychiatrists and members of the board who have examined the prisoner may be called as witnesses, and be avail- able for further questioning by the court and cross-examination by the prisoner or on behalf of the Government. At such hearing the court may in its discretion call any other witnesses for the prisoner. If upon such hearing the court shall determine that the conditions 687 62 Stat. 855. 18 U. S. C., Supp. II, § 4241. Ante, p. 686; supra. Post, p. 688. 62 Stat. 85. 18 U. S. C., Supp. II, 1 4241.