When rejected or ignored stalkers become ever more determined, turning the lives of their victims into a nightmare.
The stalking compulsion is known by psychiatrists as erotomania. The basic delusion is that the pursuer is either loved intensely by their quarry or would be if they only knew each other. Some are harmless but many are not. John Hinckley, who shot and wounded President Ronald Reagan, was trying to impress actress Jodie Foster, for whom he had formed an obsessive attraction.
Earlier this month Robert Dewey Hoskins was convicted of making "terrorist threats" to the pop singer Madonna. He broke into her Hollywood estate twice, left love letters in her letter-box and threatened to "slice her throat from ear to ear".
Other public figures stalked in recent years include tennis players Monica Seles and Steffi Graf, supermodel Naomi Campbell, singer Olivia Newton-John, and the actress Helena Bonham-Carter.
Princess Diana has been the subject of a number of obsessives. In 1990, an Iranian businessman was bound over after he climbed into the grounds of Kensington Palace to try to present her with a silver clock. Earlier this month, a German doctor was warned by magistrates not to enter the SW6 area of London where he was arrested and charged with obstruction while waiting outside the gym where the Princess has her daily workout.
Security was also stepped up for the Princess Royal amid growing concern over a "stalker" who followed her around.
Men have also been stalked by women. David Hamilton, the radio disc jockey, was stalked for three years in the 1980s by a woman listener.Reuse content