In Russell v. Commonwealth, 216 Va. 833, 223 S.E.2d 877 (1976), Virginia's highest court reasoned as follows: Use of the missing witness instruction against the defense would run head on into the presumption of innocence to which every accused is entitled and upon which juries are universally instructed. The burden is upon the prosecution to prove its case against the accused. The defense need not prove anything; it may rely upon the presumption of innocence. To tell a jury that the failure of the defense to call a material witness raises an adverse presumption against the accused is to weaken, if not neutralize, the presumption of innocence which, if given its full strength, might be sufficient to tip the scales in favor of acquittal. (Id. at 837, 223 S.E.2d at 879.)