The YouTube killer who shot dead eight members of his school in Finland before turning his gun on himself had internet contacts with an American teenager who was planning a shooting spree in a high school in Philadelphia, it was claimed yesterday.

The disclosure could turn upside down previous assumptions about the dynamics of school massacres. Until now, teenage killers were regarded as depressed loners whose imagination had been stoked by aggressive computer games. Now it seems that information may have been shared by potential killers over the internet: a virtual community of young people who idolise the 1999 Columbine High School murders.

“It’s highly probable that there was some form of contact between Pekka-Eric Auvinen and Dillon Cossey,” a spokesman for the cyber crime department of Helsinki police said. Dillon Cossey, 14, was arrested last month on suspicion of planning to storm his old school, Plymouth Whitemarsh. Police acting on a tipoff found a 9mm semi-automatic rifle, handmade grenades, a .22 pistol and a .22 single-shot rifle at his home. Less than two weeks later Auvinen, already a member of a shooting club, was buying his first gun — a .22 pistol — and expressing interest in a 9mm semi-automatic.

Police do not believe this to have been a coincidence. The two youths are thought to have made contact over two MySpace groups, “RIP Eric and Dylan” — a reference to Eric Harris and Dylan Klebold, who killed 12 schoolmates at Columbine — and “Natural Selection”.

Dillon Cossey used the alias Shadow 19462 on internet forums. Overweight and bullied, he had been withdrawn from Plymouth Whitemarsh and was resentful. His MySpace profile lauded the Columbine killers as heroes.The 18- year-old Finnish killer made a rambling testimony on YouTube, clearly drawing on the rhetoric used in the Natural Selection group and related chat rooms. His YouTube account — under the pseudonym Sturmgeist89 — included snippets from violent films, shots of him posing with his “beloved” pistol and tributes to other mass murderers. It was viewed 200,000 times before being closed down after the Finnish high school killings on Wednesday.

Police are trying to establish whether the Jokela massacre was in some way a copycat event or whether it resulted from an exchange of tips across the internet. Across Europe cyber-crime experts are nervous that some of the abuses on the net committed by Islamic fanatics could become a model for other marginalised groups. The diaries of the Columbine killers also give detailed guidance about their crime.

The two 18-year-olds in Columbine had planned to set the school on fire to spread panic. This appears to have also featured in the plans of Auvinen. However, he brought only a small quantity of lighter fuel, not enough to cause a blaze. Instead he relied on an enormous cache of ammunition for his Sig Sauer Mosquito handgun. He pumped 68 bullets into his eight victims; the 69th he shot into his own skull. Police found 500 rounds of unused ammunition in his rucksack.

“We have to look out for the warning signs,” said Tonni Karpela, a Finnish security expert. “Plainly there is a problem if a young person openly espouses violence and regards it as a solution.” Finnish authorities were trying to piece together the clues on the internet and in the classroom. More concrete measures to protect schools have been ruled out. “I am firmly against metal detectors in schools,” Mr Karpela said. “That won’t make pupils feel better or more secure.”

The Government has said that it will look again at gun control regulations but it is unlikely that they will be tightened severely. Guns are common in Finland: 56 per cent of the population owns one. Everybody over the age of 15 can apply for a gun permit; usually the applicants are hunters. Auvinen was a member of the Helsinki Shooting Club, which enjoys some notoriety in the capital. Eight years ago a member suffering from schizophrenia shot three men dead.

“If we suspect anyone of being mentally sick we will not accept him as a member of the club,” Mari Kiuru, the owner of the club, said. Auvinen showed no outward sign of psychological problems, even though his schoolmates noted that he talked obsessively about his gun.

Unlike in the case of Dillon Cossey there is no sign that Auvinen’s parents were drawn into his fantasy world. Dillon Cossey’s mother has been arrested in America for buying weapons for her son. Auvinen’s parents are regarded as somewhat bohemian in the small dormitory township of Jokela. His father plays part time in a jazz band and composes his own music; Auvinen’s mother is an activist for the Greens. They are regarded as stalwart members of the community and neighbours describe them as a “normal family”. Since Wednesday they have been living under police protection.

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