Mark Chapman's shooting of John Lennon on the doorstep of the star's New York home shocked the world. That Chapman was a fan, and someone who craved celebrity himself, only added to the chilling unreality of the moment. 'The world is not like the Sixties,' Lennon said in the last interview before his death. 'The world has changed.' The first, and most chilling, manifestation of the dark side of our obsession with celebrity.