Even before his life became consumed with collecting knives and finding money for the next Friday night vodka-and-lager binge, Alan Pennell was never easy to fathom.

Even before his life became consumed with collecting knives and finding money for the next Friday night vodka-and-lager binge, Alan Pennell was never easy to fathom.

The roots of his descent into crime, which culminated yesterday in a life sentence for the murder of 14-year-old Luke Walmsley, can be traced back to his troubled early childhood.

As a small child, Pennell, now 16, was often taken to Donna Nook, a stretch of coast near his home in the Lincolnshire village of Binbrook, south of Grimsby. There were superb sands there, fine views of seals and hordes of children to run around with, but young Pennell, a quiet, sensitive child, settled for solitude.

There was one subject guaranteed to shake Pennell out of his introspection, though. His mother, Denise Pennell had raised him and his sister alone and his inclination to defend and protect her was unmissable.

That was before the most significant event in his life - Mrs Pennell's death in a high-speed car crash in 1994. She and her boyfriend were three times over the drink-drive limit. At the time, Pennell was six.

One of Mrs Pennell's closest friends, who lived a few doors away, recalled yesterday how Pennell's sensitivity about his mother remained. "It upset him because of the way she died," said Mrs Cordwell-Hannigan, 43. "He was protective of his mum and would not hear anything said against her. He never got over the loss."

Her 16-year-old daughter Kaylea, who had joint birthday parties with Pennell in Binbrook, has the same recollection: "He was close to her."

Pennell and his sister moved in with their father, Robert, a long-distance lorry driver who was often away. Their new home - a semi-detached farm cottage surrounded by fenland in Grainthorpe - was far more isolated and Pennell seems to have gone quickly off the rails.

Neighbours recall how he spent much of his youth getting drunk and hanging around with a succession of girlfriends, including Luke Walmsley's 12-year-old sister, Lauren. Pennell comfortably dominated any peers who challenged him and by last year he was coming to the attention of the police for using violence.

In June 2003, he received a police reprimand for assaulting a police officer - though not injuring him. Two months later he received an official police warning for punching a fellow pupil three times in the face, loosening the child's tooth and giving him a swollen lip.

Psychiatric reports revealed in court yesterday talked about Pennell's inability to control his anger. There was no better evidence of that fact than a schoolyard discussion on the morning of Luke's murder about whether the football team Manchester United were "crap". When another boy challenged him on the matter, he held a knife to his throat.

Having another pupil stand up to him was an alien experience and Pennell knew he faced a formidable adversary in Luke Walmsley - whose intelligence, physical stature and sporting success were all superior.

A combination of factors appear to have amplified the insecurities felt by the diminutive Pennell in the fortnight leading up to the murder. He and Luke fell out over his split with Luke's sister; Luke overcame Pennell's best friend in a fight; and Pennell discovered that Luke had been passing notes to his new girlfriend during lessons talking about a fight between the pair. There was also a suggestion that Luke had made derogatory remarks about his mother.

But the ultimate motive may have been fear of losing face. Pennell had threatened to stab Luke to death on a number of occasions and felt he had to follow through. "Once he gets it into his head that he's going to do something you can't stop him," his best friend said.

In the aftermath of the murder, police searched Pennell's home and found his makeshift attempts to fashion a place of security for himself. It was a hut next to his father's house, converted into a home. A "members' only" sign was above the door and there was a 6ft snooker table, a single bed, a stereo and a sofa. Here, his collection of violent martial arts videos and knives were found.

After the murder, Pennell was questioned by a doctor about his three wishes. He replied that he wanted to bring his mother back and to take time back to before the incident. He could not think of a third.