Is it improper for a prosecutor to suggest that information not presented to the jury supports witnesses' testimony?

It is improper for a prosecutor to suggest that information not presented to the jury supports witnesses' testimony. United States v. Molina, 934 F.2d at 1445. The "invited response" doctrine, however, is an exception to this rule of impropriety. Id. at 1445 n. 4. If the prosecutor's remarks were "invited" by defense arguments and did not more than respond substantially in order to "right the scale," such comments do not unfairly prejudice the defendant and therefore do not warrant reversing the conviction. United States v. Young, 470 U.S. at 12-13.