The sole issue on appeal was whether the district court abused its discretion under Daubert by admitting expert testimony concerning DNA evidence. Focusing on the deferential standard of review, the Court rejected the defendant's arguments that the expert's methodology was unreliable because of the low quantity DNA mixture present and the absence of appropriate validation testing and interpretive thresholds for complex mixtures. The Court found that the defendant's arguments went to weight rather than admissibility. And, although the defendant identified newly-available scientific journals that bore on the reliability of the expert's methodology, the Court declined to consider them, because they were not included in the district court and were not a part of the record on appeal. Where newly-discovered evidence undermines the validity of the conviction, the defendant may seek a new trial in the district court; but an appellate court may not consider that evidence for the first time on appeal and make factual findings. Finally, the court held that the admission of the DNA evidence was harmless in any event because the other evidence of guilt was overwhelming.