Preview: The Killing Of John Lennon, Edinburgh International Film Festival, Edinburgh

A stalker who shocked the world

Like most people who are old enough, the writer and director Andrew Piddington remembers what he was doing when he heard John Lennon had been shot in December 1980. "I was making a series of films for television that had a lot of Beatles archive material in them," he recalls, "so it was very pertinent."

Although not especially a fan of The Beatles' music, the man behind the feature film about Lennon's assassin, Mark Chapman, does insist: "I believe very much in the spirit of John Lennon and I dislike intensely the nature of the man who brought him down."

Piddington knew he was dealing with a sensitive subject in dramatising the story after last year's Channel 4 documentary I Killed John Lennon was criticised by the musician's family for supposedly glorifying Chapman, yet he had compelling reasons to make it. "This film does not set out to exonerate Chapman in any way," he says. "He was very calculating, very cold and the interesting psychosis of the man is one reason for making this film. The story needs to be told because it's another way of gaining insight into what these narcissistic people are driven to do."

Piddington filmed over three years in Hawaii, Georgia and New York, and researched the film using a combination of press cuttings, police files and books from around the time of the shooting. "It's all based on firm, hard evidence," he says. He specifically chose newcomer Jonas Ball to play Chapman to avoid "the baggage you have with a known actor".

Piddington says he is looking forward to "opening up a dialogue" on The Killing of John Lennon at the 60th annual Edinburgh International Film Festival, as he believes the story has added resonance in today's celebrity-obsessed world. "Chapman was the first celebrity stalker," he says. "That's as interesting today as it was then."

Edinburgh International Film Festival 14 to 27 August; 'The Killing of John Lennon' is shown on 15 and 16 August ( www.edfilmfest.org.uk)