13. Haupt had abandoned the plot by then as well
The FBI agents followed Herbert Haupt about Chicago for the next three days in the hope that he would lead them to the sole remaining conspirator, Hermann Neubauer. Neubauer was staying at the Sheridan Plaza in Uptown Chicago, going to movies to pass the time. On Saturday, June 27, the FBI was tired of following Haupt and arrested him. Haupt quickly told them where Neubauer was staying and the FBI staked out the hotel. Neubauer was returning from a film that night when the FBI took him into custody. Once the Chicago office notified Ladd in Washington that the last suspect was accounted for, the FBI arrested Dasch, who up to then believed he was a cooperating witness and would be immune from prosecution.
Dasch’s most immediate concern was that his colleagues would learn that it had been he who revealed the plot to the FBI. He asked to be held with them to alleviate their concerns, though there is evidence Burger had already shared the story with his fellows. Nonetheless, Hoover agreed with the request for his own personal reasons. Hoover wanted the Germans to be impressed with the efficiency of his bureau, in the hope it would dissuade the Abwehr from further such operations (which at the time were in the works). He also wanted President Roosevelt and the general public reassured that the FBI was diligently protecting the American people from Nazi infiltration.