Jurors were told that the teenager accused of murdering Bailey Gwynne carried weapons to school to stop people bullying him about his weight.
Bailey was killed during a lunchtime fight with a fellow pupil at Cults Academy, one of Scotland’s best-performing state schools.
The accused accepts killing him by stabbing him once through the heart, but denies murder.
Yesterday the High Court in Aberdeen heard evidence from the accused’s best friend who witnessed the whole tragic incident.
Giving evidence in his distinctive green blazer and school tie – the same uniform worn by both boys on October 28 – the teenager said he had seen his friend with a knife at school around 20 to 25 times before the killing.
And he went on to say the accused would also carry one of two knuckledusters he had bought on eBay with him at least a couple of times a week.
He also told the court that his friend had been in possession of a knife at the school either one or two days prior to the fatal attack.
Prosecuting the case, advocate depute Alex Prentice QC asked the witness if he had ever confronted his friend about the knife.
The youth said: “I said ‘you shouldn’t have that kind of stuff in school, you’re too young for that, you might get into trouble’, but he thought it was cool so he didn’t listen.”
However, counsel for the accused, Ian Duguid QC, claimed his client had the weapons with him to stop him being bullied.
He put it to the witness that his client had stopped attending PE classes in the weeks leading up to the incident as he was being teased “for having breasts”.
Mr Duguid asked: “Do you know if other people in the school knew he carried a knife or knuckle duster?”
The witness replied: “Yes.”
Mr Duguid continued: “How did the word get out that he was carrying theses items?”
The witness replied: “The knife was not well known but quite a few people knew about the knuckleduster.”
Mr Duguid asked the teen: “Why do you think someone who traditionally is not a fighter or aggressor gets himself items to help him look cool? Why do you think he would do that?”
The youth said he didn’t know.
Mr Duguid continued: “Did he ever explain to you that he was carrying these items to stop people giving him a hard time about his weight?”
The witnesses said that he had not.
The court heard the lunchtime brawl began after insults were exchanged, and Bailey was heard to call the accused fat.
The witness said the accused responded by insulting Bailey’s mum and before he knew it Bailey, who was 6ft 1in, was “towering over” the accused.
He said: “I found it really shocking because he’s really quiet and he’s known not to fight back. People thought he didn’t have the guts, to be honest.
“The accused pushed him back and they both started fighting. Bailey had the accused in a headlock and he was trying to get out of it and Bailey just kept hitting him against the wall.”
The witness said that this was the moment when he saw the accused reach into his blazer pocket and take out a knife, which he “thrust into” Bailey.
He said no one seemed to realise, apart from himself and the accused, that Bailey had been stabbed immediately after the incident.
He said: “I don’t even think Bailey knew. They made him walk all the way along the corridor before he collapsed. They didn’t even carry him, but I don’t think they realised.”