D.C. Code § 16-1357
When the date for trial has been set, as provided by section 16-1356, the court shall order the names of a number of persons, not less than twenty, selected from the special jury list provided by section 16-1312, and the names of the persons selected shall be certified to the clerk of the United States District Court for the District of Columbia as a panel of prospective jurors. The persons so certified shall be thereupon summoned by the United States marshal for the District of Columbia to appear in the court on the day specially fixed for the trial of the cause. Before selecting or impaneling the jury, the court may cause a second, third, or other further list of prospective jurors to be drawn, certified and summoned in like manner. From the persons so certified and summoned, the court, after examination on oath and in open court as to their qualifications, shall select and impanel a jury of five capable and disinterested persons who have the qualifications of jurors as prescribed by law for the courts of the District of Columbia, and in addition thereto are not in the service or employment of the United States or of the District of Columbia.
D.C. Code § 16-1357