In Powell v. Commonwealth, 13 Va. App. 17, 23-24, 409 S.E.2d 622, 626 (1991), the Court distilled from several cases the principles that govern the Commonwealth's impeachment of a defendant with the defendant's prior convictions. The Court held where a defendant/witness testifies untruthfully on direct examination about the number of prior felony convictions, he opens the door to cross-examination which is reasonably designed to elicit relevant evidence to show whether the defendant/witness knowingly testified falsely. The Commonwealth may not, however, resort to cross-examination which unnecessarily presents prejudicial information about the name or nature of prior convictions with little or no probative value. Id. at 24, 409 S.E.2d at 626.