reveal what alerted them to Koecher's treachery. Koecher and other KGB officials claim it was Kalugin. Another suggestion by a CIA historian, is that it was the StB intelligence officer, Jan Fila, who betrayed him with the latter disappearing in December 1989, a month after the Czechoslovakian Velvet Revolution. Apprehension The FBI apprehended Koecher on 27 November 1984, outside New York City's Barbizon Plaza Hotel, and brought him and, soon afterwards, his wife Hana in for several days of questioning. Finally, Koecher agreed to become a triple agent working for the Americans, provided that they agreed to grant him immunity from prosecution. This was done and Koecher attempted to convince the FBI that he was cooperating. However, it was then decided that Koecher was not reliable enough to be a triple agent and was likely to defect and return to Czechoslovakia. On November 27, 1984, the day after the couple sold their apartment and hours before they were scheduled to fly to Switzerland, Koecher and his wife were arrested in New York City. Koecher was held on espionage charges and Hana Koecher as a material witness. The arrest of the two agents was released to the media. U.S. Attorney Rudolph Giuliani led the case. The case on his wife, Hana, a purported diamond merchant but actually a courier for the StB from 1974 to 1983, had been bungled and would not result in a conviction, so the prosecutors allowed her to gain immunity in return for information against her husband Karl Koecher. 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