An ultra-violent South Korean revenge thriller may have partly inspired the massacre. In videos that he posted to NBC in New York on the day of the killings, Cho Heung Sui imitates two distinctive images from Oldboy, which won the Grand Jury Prize at the Cannes Film Festival in 2004.

The South Korean-born student depicts himself wielding a hammer in imitation of the film’s hero, who embarks on a murderous rampage against the people who held him captive for 15 years and destroyed his life. Elsewhere in the videos, filmed over six days, he holds a gun to his head, copying another scene from the film.

Korean cinema has built a strong critical and commercial following in the West in recent years, winning a reputation for stylishly shot, violent thrillers. Oldboy, directed by Chan Wook Park, was hailed as an existentialist masterpiece by some reviewers on its release. Others were disgusted by the level of violence and a scene where a live octopus is eaten.

Unhappy schooldays play a role in the plot. Oldboy was the second film in Park’s acclaimed Vengeance trilogy. In an interview with The Times in 2004, its star, Min Sik Choi, described his character as “the loneliest, most miserable character on Earth . . . like a dry wooden block with only revenge on his mind and nothing else, not even emotion.”

Unexpectedly the character’s killing spree helps him to become more human, he added, “like moss growing on a wooden block after it gets wet”.

Nick James, editor of Sight and Sound, the film magazine, said: “Oldboy is a very, very distinctive film and the most highly regarded of the films now labelled Asian Extreme cinema but it is also so ludicrously over the top that no sane person could mistake it for reality.”

Oldboy is not particularly exceptional in its level of violence (compared with other Korean films) but it is exceptional in being more imaginative than most of them. “It’s an Oedipal drama that plays out through all sorts of revenge themes. People who are disturbed will find things that reflect their disturbance.

“I don’t think there’s a case of cause and effect here. It’s not the movies that are the problem — it’s the guns.”

Other cultural clues to Cho’s state of mind were being debated on the internet yesterday. Another pose in the NBC videos shows him holding guns in both hands. It recalls the films of the Hong Kong action director John Woo and a publicity shot of the actor Laurence Fishburne, used to promote The Matrix Reloaded in 2003. A play attributed to Cho, called Mr Brownstone, features students who claim to have been raped by their teacher singing lyrics from a Guns 'n’ Roses song of the same name, which is about heroin abuse.

Similar speculation linked the perpetrators of the Columbine High School massacre to The Matrix, The Basketball Diaries and Heathers. Bob Cesca, a film-maker blogging on The Huffington Post, dismissed the connection as “the most ridiculous hypothesis yet”.

Police and the media were alerted to the video’s similarities with Oldboy by Professor Paul Harris, a lecturer at Virginia Tech.

Film buffs responded warily to the links. Nikki Finke, the Deadline Hollywood columnist for LA Weekly, said it was “just a matter of time before the Virginia Tech massacre was linked to the movie industry”.

Monika Bartyzel, blogging on Cinemtical.com wrote: “How many people mimic media when committing terrible acts compared to how many people watch the media and go on with their lives? I would imagine that it is similar to the chances of getting hit by lightning.”

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