The killers, aged 17 and 18 at the time of the murder, have offered few clues. Inarticulate and often monosyllabic under questioning, they could not, or would not, shed light on an appalling and apparently uncharacteristic burst of violence during the attack in woods near their rooms at Hadlow Horticultural College, near Tonbridge in Kent.
All the boys would say was that Russell was bullying them and "getting on their nerves". Such a mundane explanation only highlights the horror of the crime. So it was with the murder trial four and a half years ago of teenagers Richard Elsey and Jamie Petrolini, who were both 18 and attending an Oxford A-level crammer, when they ambushed a driver in London's West End. They slit Egyptian businessman Mohammed el-Sayed's throat and stabbed him repeatedly until the interior and windscreen of his car were swimming in blood.
It is impossible for anyone who sat through both court cases not to be struck by disturbing similarities. The boy killers were all polite and law abiding, from comfortable, middle-class homes. But all were regarded as loners. They also shared an obsession. At the Old Bailey trial in 1994 it emerged that Elsey and Petrolini were fixated on the SAS. During their year in Oxford they came to share a private fantasy world in which Elsey, described by other students as the more clever and dominant, somehow managed to persuade Petrolini that he was the youngest lieutenant in the SAS and that he could train Petrolini for the elite unit. Petrolini would march through Oxford with Elsey bawling orders in his face. The two would take off, blacked up, at night on increasingly bizarre secret manoeuvres and missions. They were obsessed with death and violence. The murder of Mr Sayed was the execution of their ultimate mission; the murder of a stranger had been fantasised about for months. Petrolini insisted later that he believed the murder was his SAS initiation test.
Friends of Sayers, Wallis and Russell Crookes told the Maidstone Court last month that the trio - once inseparable - were also obsessed with the SAS. Student Darren Rifat recalled that they constantly read SAS books and that when they watched war videos, they would replay the goriest bits, laughing when people were shot and fell down.
The three would go out to a copse in woods near the college a few nights a week. They called the spot The Training Ground and themselves The Brotherhood, after a computer war game. They sometimes stayed out all night, coming back too tired to make their first class. On the night Russell was murdered, the three were off on their own again in the woods.
According to Rifat, Russell Crookes, 6ft and 14 stone, was the dominant member of the group. Sayers was next in the "ranking" and Wallis trailed in last. But in the weeks running up to the murder there was clearly conflict in the ranks. Sayers complained to other students that Crookes had punched him and students said it was obvious that Sayers and Wallis were avoiding him. According to Wallis, who, unlike Sayers, admitted murder, the decision to get rid of Crookes was made three weeks before.
There was premeditation in both murders. And callousness. Wallis and Sayers went back to college for orange juice and biscuits before returning to burn the body. On the bus journey Elsey and Petrolini made back to Oxford after their murder, Elsey fell asleep and Petrolini opened his birthday cards.
But do the similarities offer any clues as to why teenagers, with no previous history of violence, commit murder? Kevin Epps, a clinical psychologist who works with young people who have committed murder, rape and arson, describes adolescence as a potentially dangerous place. It is a developmental period, where there is a shift in styles of thinking and a struggle for independence and identity.
Sexual identity in particular can be a thorny, threatening issue. At Maidstone Court students said Sayers was called Fruit Bowl "because of the way he walked" and Wallis was picked on because he "was a bit camp". Russell Crookes called Graham "Gayham". And on the night Crookes was discovered to be missing, his father claims Sayers complained that he had called him and Wallis "pansies". In the Old Bailey in 1994 sexual identity also featured, with Petrolini's confession to a psychiatrist that he thought of Elsey while masturbating.
Adolescents who are isolated from their peer group - and victimised or bullied - often fantasise about being powerful. "The trigger for violence can be when you meet someone who shares your view of the world," says Mr Epps. "The other person can reinforce your fantasies, and your sense of being right, and halve your responsibility."
Dr Sue Bailey, a psychologist at an adolescent unit in Manchester, says that only a very small proportion of children and young people who kill could be regarded as mentally ill. She believes any search for answers should begin with an acceptance of the strength of fixations even in a normal adolescence. She says there is a significant group of youngsters - usually boys - who seem to have everything going for them but none the less veer off the usual path into areas like violence.
"When you have more than one child thinking the same unpleasant thoughts they fuel each other," she says. Violent fantasy becomes a reality when a member of the duo, or the group, cannot back down. Wallis told the court he did not believe the murder would take place, despite days of planning, until it was happening, though he admitted he did not try to stop it once it was underway. In fact, he joined in the stabbing.
Whether the videos Sayers and Wallis watched fuelled violent fantasy is not certain. The judge asked Wallis more than once if he had read or watched accounts of young men killing friends. Wallis said he had. Last year new research by Professor Kevin Browne of Birmingham University concluded that a violent family background had more bearing on criminality than violent videos. But it also found that violent videos acted as a catalyst in violent crime. That might apply as much to the carnage at Denver's Columbine High School, as one terrible murder at Hadlow College.Reuse content