DALE Robertson's killers spent their time posturing with weapons on social networking websites, indulging in anti-social behaviour, and styling themselves as members of the 'Parson X Crew'.
But the detective in charge of the murder investigation said today the groups were not sophisticated or organised criminal gangs, but merely groups of youths who gave themselves gangster-style labels.
Dale, aged 18, was stabbed through the heart when he stepped in to help settle a dispute over the alleged theft of Xbox games, after a 16th birthday party spiralled out of control and spilled onto the streets of Sheffield in September last year.
Today, Detective Superintendent Richard Fewkes, head of South Yorkshire Police's major incident team, said Dale's death was the result of a breakdown in society and a lack of role models for young men.
He said: "It's such a tragic waste of a young man's life and, when you look at the motivation for the murder, it's such a trivial issue. It's so sad that somebody's life is lost so cheaply."
READ MORE IN OUR SPECIAL REPORT:Teen killed in row over computer gameLoving brother too lively to diePart truths of witnesses'Det Supt Fewkes said of the gang which attacked Dale: "These are people who have been involved in anti-social behaviour and low level crime.
"Their willingness to use weapons is reprehensible but it is often a plague within the communities in which they live.
"They are very chaotic individuals in the lifestyles they lead, and the contribution they make to society is minimal. The behaviour they displayed in this went far beyond what is acceptable in society."
Groups of youths in the area included the Margot Crew - a group which hung around the Margetson shops in Parson Cross - and the Parson X Crew whose members were at the party. Its affiliates included Travis Hurst, 18, and Spencer Jessop, 17, the two teenagers found guilty of violent disorder in relation to Dale's death.
Det Supt Fewkes said youths on Sheffield's estates - who 15 years ago might have hung around drinking on street corners causing a nuisance and intimidating old ladies - were now increasingly prepared to use gratuitous violence and arm themselves with weapons.
The knife used to stab Dale was brought to the party by one of the youths.
Jurors convicted Seaon Thompson, 16 now but 15 at the time, and Reece Mendez, 17, of murder on the grounds of joint enterprise, but were unable to decide who delivered the fatal blow to Dale's heart and lungs.
The murder weapon was flung into a back garden yards from the crime scene.
Det Supt Fewkes said Dale's death was not the result of a feud between the gangs but resulted purely from a dispute over the theft of Xbox games from the party.
He added family breakdown in society had left youngsters without role models.
Det Supt Fewkes said: "These men are unrepresentative of the majority of young people in Sheffield, but they are the ones grabbing the headlines."
He said South Yorkshire Police and Sheffield Council were working to intervene and target youngsters at risk of becoming involved in crime and anti-social behaviour.
"I think there is a culture in society that drives this behaviour, possibly because of the roles of families in society and who the young people look to in terms of leadership or role models within communities.
"A lot of these issues are being dealt with by police, local authority, education department, social services and youth offending teams.
"There is a lot of work that has been going on and it is having a positive impact on the use of violence among young people.
"The fruits of some of that will probably not be realised for a number of years. A lot of energy is going into trying to address the issue."
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