h Cir.1980); United States v. Osborn, 561 F.2d 1334, 1338-39 (9th Cir. 1977); In re Subpoena Addressed to Murphy 560 F.2d 326, 331 (8th Cir.1977); Hartford Assocs. v. United States, 792 F.Supp. 358, 367 (D.N.J.1992), it bears the burden to rebut the presumption that tainted material was provided to the prosec