Marquez-Urquidi v. United States

holding that weight of evidence is exclusively for finder of fact who is free to believe all, part, or none of evidence and to determine credibility of witnesses | noting that Smith does not bind Pennsylvania courts and declining to extend use immunity to a defense witness where appellant failed to demonstrate that such testimony was clearly exculpatory | explaining that weight of evidence is exclusively for finder of fact; appellate court cannot substitute its judgment for that of fact-finder | stating where trial court has ruled on weight claim, appellate court’s review is limited to whether trial court palpably abused its discretion in ruling on weight claim | stating: where trial court has ruled on weight claim, appellate court’s role is limited to whether trial court palpably abused its discretion in ruling on weight claim | explaining weight of evidence is exclusively for finder of fact who is free to believe all, part, or none of evidence and to determine the credibility of witnesses; appellate court cannot substitute its judgment for that of finder of fact