Although the police did not identify the suspects, one television network showed details of the website run by one, a school student whom neighbours said was obsessed with violence and had threatened to kill other students.
The page, amended just hours before he calmly walked into his school and killed up to 23 schoolmates and teachers, is a chilling testimony to an individual's obsession with violence, fed by pop culture. He talks of a chilling day that will come which he refers to as "NBK" - perhaps standing for Natural Born Killers. It was unclear last night whether it was a coincidence that the killers chose 20 April - Adolf Hitler's birthday - on which to launch their killing spree.
The website quotes from a song, "Son of a Gun", by the German anarchist band Kein Mehrheit fur die Mitleid, which loosely translates as "no sympathy for the majority". The song continues: "What I don't do I don't like, what I don't like I waste."
The website goes on to talk about building pipe bombs. "Pipe bombs are some of the easiest and deadliest ways to kill a group of people." It adds: "Shrapnel is very important if you want to kill and injure a lot of people." The site refers to NBK as an event which is approaching when the pipe bombs will be used.
At another address on the website there is a sketch, apparently by the suspect, of someone wearing dark glasses and shooting people with a machine gun.
Last night the killers were said to be members of an anti-social clique who dressed in long coats and dark glasses and were known as the Trenchcoat Mafia. They were described as a group of up to 10 students who mixed only with themselves and were fans of the heavy metal singer Marilyn Manson.
It was suggested the group may have been responsible for racist daubs in Columbine High School. However, in the near hysterical atmosphere after the shootings, it was impossible to ascertain whether the group was genuinely sinister before this incident or were simply a group of disaffected, but not unusual, teenagers.
Dave Hnida, school team doctor at Columbine, said he believed the gang were classic misfits. "They did wear all-black trench coats and sunglasses all the time," he said. "They didn't really associate with anybody else at the school. One thing I remember is an entry by one of them in the school yearbook, saying: `Who says insanity is crazy? Insanity is healthy.'"
He went on to say that the gang may have been responsible for daubing swastikas at the school several years ago. "There had been an incident where some swastikas were painted on lockers at the school, but it's much too early to say whether that's connected with this incident."
One student, Josh Nielsen, said they were known as the Trenchcoat Mafia. Classmate Jason Greer added: "They are jerks. They are really strange, but I've never seen them do anything violent."Reuse content