His acrimonious departure from the neo-Nazi community and the publication of his books, "Die Abrechnung: Ein Neonazi steigt aus" written with Winfried Bonengel in 1993 and "Führer Ex" written with Tom Reiss in 1996, caused his former comrades to send him a letter bomb disguised as a book, which package was opened by his mother, without however sustaining injury. Hasselbach then confessed his accumulated knowledge about the neo-Nazi community to the German Federal Criminal Police Office. He did not only incriminate others but also himself. In 1997 he was given a two-year suspended sentence for an admitted fire-bombing of a left-wing, alternative youth club.