In United States v. Diggs, 560 F.2d 266, 268 (7th Cir.), cert. denied, 434 U.S. 925 (1977), the appellant was convicted of falsifying his sworn testimony in front of the grand jury. At the grand jury hearing, the appellant denied that he delivered, saw, or knew about a box containing a machine gun that was delivered to the house of Halbert Vanover. Id. At the appellant's perjury trial, however, Vanover testified that the appellant had delivered a box to his home, and that, when Vanover brought the box inside his house and opened it, he saw that the box contained a machine gun. Id. Three other witnesses also testified on behalf of the government, all stating that they had seen the box in Vanover's home, although none had actually seen the appellant deliver the box. Id. The Seventh Circuit held that this testimony was sufficient to meet the two-witness rule, because the testimony of three independent witnesses corroborated the principal witness's testimony. Id. at 270. In reaching that conclusion, the Court noted: No wording of the two-witness rule requires the corroborative evidence to be sufficient for conviction; nor does any phrasing permit conviction where the corroboration consists of merely peripheral testimony not tending to show the falsity of the accused's statements while under oath. The two-witness rule is thus satisfied when there is direct testimony from one witness and additional independent evidence so corroborative of the direct testimony that the two when considered together are sufficient to establish the falsity of the accused's statements under oath beyond a reasonable doubt. "Independent" evidence in this context means evidence coming from a source other than that of the direct testimony. This independent corroborating evidence must be trustworthy enough to convince the jury that what the principal witness said was correct, the ultimate determination of its credibility being an exclusive function of the jury. As in all criminal cases, the burden on the Government against which its evidence must be judged is that of proving the defendant guilty beyond a reasonable doubt. The two-witness rule in perjury cases merely imposes an evidentiary minimum required to meet this burden as a matter of law. The rule focuses on the totality of the Government's evidence in order to assure a sufficiency necessary to fulfill its underlying policy that perjury convictions not be based merely on an "oath against an oath." Id.