881 F.2d 878, 886 (10th Cir.1989) (because the government witness’s “credibility had been placed in issue by the defense,” evidence corroborating that witness’s testimony was “relevant for the purpose of overcoming that attack”). Indeed, evidence concerning a witness’s credibility is always relevant, because credibility is always at issue, see United States v. Universal Rehab. Servs. (PA), Inc., 205 F.3d 657, 666 (3d Cir.2000) (en banc) (noting that “[jjurors are instructed, ... in almost all cases, that they are to determine the credibility of all witnesses who testify.... even in the absence of an affirmative challenge to witness credibility”), especially when the witness is testifying for the government in a criminal trial. United States v. Gambino, 926 F.2d 1355, 1363 (3d Cir.1991) (<HOLDING>). Third, and contrary to Green’s argument on
recognizing that in any criminal trial the credibility of the prosecutions witnesses is central holding trial court free to evaluate credibility of witnesses holding that the postconviction court is the sole judge of the weight of the evidence and the credibility of witnesses holding trial court is sole and exclusive judge of witnesses credibility recognizing trial courts superior vantage point in assessing credibility of witnesses