The district court erred here in rejecting defendants’ claim that a juror concealed his racial bias without making any findings concerning whether the juror actually made a racist statement, and if so, its specific content. The lack of findings leaves nothing for the appellate court to review. It is unclear whether the district court found no racists statements were made, or simply that the statements made were not sufficient to establish that the juror lied during voir dire. Jury tampering, which creates a presumption of prejudice which the government must rebut, is qualitatively more prejudicial than other kinds of extraneous influence on the jury deliberations, because it goes to the heart of the Sixth Amendment’s promise of a fair trial. To show jury tampering, the defendant must first make a prima facie showing that the intrusion had an adverse effect on the deliberations. This is a low standard, and unless the showing is entirely frivolous or wholly implausible, the court should order a hearing to explore the degree of intrusion and likely prejudice to be suffered. Here, the court heard the co-defendants’ claims of jury tampering by another co-defendant as part of a new trial motion. In denying the motion, the district court applied the incorrect legal standard of whether the jury was “substantially swayed” by the misconduct. The district court therefore made its decision on the “overwhelming evidence” of defendant’s guilt, rather than considering the effect of the bribery attempt on the course of the jury deliberations. The prima facie case was made here and the matter was remanded for a prejudice hearing. The Court of Appeals ordered the convictions vacated unless the government could show no reasonable possibility that the deliberations were affected by the tampering. The Court of Appeals advised that the rule prohibiting invading the jury’s thought-processes would not bar the introduction of evidence concerning the jurors’ fear or anxiety about their own well-being during deliberations.