Criminologist David Wilson shares his story of being stalked

Next month a new documentary will investigate the infamous stalker who trailed ABBA’s Agnetha Fältskog for years. Gert van der Graaf became obsessed with the singer - moving to her neighbourhood and turning his house into a shrine to her. But what causes a person to become a stalker? Criminologist David Wilson will be explaining the psychology of a stalker’s mind and sharing his own story of being stalked.