Luke Walmsley was stabbed through the heart

The student, who cannot be identified, described how Luke Walmsley, 14, was attacked at Birkbeck Secondary School in Lincolnshire.

The boy said he was left shocked as Luke's alleged attacker walked off shrugging his shoulders.

The 16-year-old defendant has denied the murder charge at the trial at Nottingham Crown Court.

'Shrugged shoulders'

The prosecution alleges the boy armed himself with a knife on the morning of 4 November 2003 before telling other students he intended to stab Luke.

The first of several child witnesses from the school in North Somercotes told the court via video link: "We were stood outside the prep room. Luke came out of the science room.

"It looked like (the defendant) punched him, but when he pulled the knife out I realised it was blood splattered up the side of my face.

"I saw the knife because he put it behind his back.

"He brought the knife out and he shrugged his shoulders, I think.

"I thought 'Why did he do it?'"

'All over'

A number of students gave evidence at Friday's hearing.

Another said: "(The defendant) got this knife out of his back pocket and he was flicking it about.

"I went 'what are you going to do with that?'

"He said: 'You'll find out in a minute'.

"Seconds later, Luke Walmsley came out and he just stabbed him. That was it. It was all over."