Is suppression of evidence sufficient to warrant a new trial?

In Barbee v. Warden, 331 F.2d 842 (4 Cir. 1964), ballistic reports and fingerprint tests tending to show that a revolver different from defendant's own had been used, were deliberately suppressed by the police. Finding that the police reports in question "had substantial evidentiary significance" id. at p. 844, the court held that the lack of the prosecutor's own knowledge about the suppression of evidence did not prevent the ordering of a new trial. We do not doubt that in such circumstances, suppression by the police rather than the prosecutor is enough to warrant a new trial.