The appellant, Pedro Anthony Perez, Jr., was convicted on the trial for one offense and entered a plea of guilty of another. He seeks, by a motion under 28 U.S.C.A. § 2255, to have the sentences imposed against him set aside on the ground that the grand jury which indicted him was composed only of persons who were registered voters on the rolls of the State. The district court denied the motion. The objection, if it be a valid one, can be availed of only before trial. It cannot be asserted in a proceeding under Section 2255. Rule 12 Fed.Rules of Crim.Proc. 18 U.S.C.A.; United States ex rel. Jackson v. Brady, 4th Cir. 1943, 133 F.2d 476, cert. den. 319 U.S. 746, 63 S.Ct. 1029, 87 L.Ed. 1702, reh. den. 319 U.S. 784, 63 S.Ct. 1315, 87 L.Ed. 1727. The order of the district court is

Affirmed.