 He is the only one of the surviving terrorists to consent to interviews since 1972, having granted an interview in 1992 to a Palestinian newspaper, and having briefly emerged from hiding in 1999 to participate in an interview for the film "One Day in September", during which he was disguised and his face shown only in blurry shadow.Of those believed to have planned the massacre, only Abu Daoud, the man who claims that the attack was his idea, is known to have died of natural causes.Historical documents released to "Der Spiegel" by the German secret service show that Dortmund police had been aware of collaboration between Abu Daoud and neo-Nazi ( E. W. Pless and, since 1979, officially named Willi Voss) seven weeks before the attack.