However, opponents of the sabotage hypothesis argued that only speculation supported sabotage as a cause of the fire, and no credible evidence of sabotage was produced at any of the formal hearings. Erich Spehl died in the fire and was therefore unable to refute the accusations that surfaced a quarter of a century later. The FBI investigated Joseph Späh and reported finding no evidence of Späh having any connection to a sabotage plot. According to his wife, Evelyn, Späh was quite upset over the accusations – she later recalled that her husband was outside their home cleaning windows when he first learned that he was suspected of sabotaging the "Hindenburg", and was so shocked by the news that he almost fell off the ladder on which he was standing.