It soon emerged that the FBI had badly blundered. Koecher's confession was given only after his interrogators promised him immunity as a ruse, and was thus invalid. His wife had been denied access to a lawyer despite frequent requests for one, which reportedly caused Justice Department officials to refuse to charge her. She refused to testify against Karl, asserting spousal privilege, though prosecutors argued this did not apply given the two had been partners in crime. With little concrete evidence, it appeared that Koecher had a good chance of being acquitted. The issue of whether or not Hana Koecher could be compelled to testify against her husband went before the US Supreme Court but the fact that both spouses were returned to Czechoslovakia in a prisoner exchange before the court's opinion was published rendered the case moot. According to Koecher, Rudy Giuliani, as a prosecutor for the Southern District of New York, had bungled the case and was unable to gain enough evidence to convict Koecher after Koecher's arrest and instead offered immunity to Koecher in exchange for more information.