A jury has been urged to convict a 16-year-old boy of murder following a school stabbing in which the Crown said he displayed "wicked recklessness".

Bailey Gwynne died of a stab wound to the heart at Aberdeen Royal Infirmary following the incident at Cults Academy on October 28 last year.

A 16-year-old boy, who cannot be named for legal reasons, is on trial accused of his murder at the High Court in Aberdeen.

He is also accused of having knives and knuckledusters on various occasions between August 1, 2013, and the day of the stabbing.

On Monday, the fifth day of the trial and just before the jury retired to consider its verdict, advocate depute Alex Prentice told the jury: "I invite you to find [the accused] guilty of [all three charges].

"Why on Earth would you carry these things? A knife and a knuckleduster have no other purpose than to cause injury.

"In this case there was a stab wound to the heart inflicted by a lethal weapon routinely carried by [the accused]. If you have a knife, you have the ability to use it.

"I don't suggest [the accused] set off in the morning intending to kill Bailey. But if he had not had a knife the outcome of the fight would have been a few bruises.

"This is not a self-defence case. I suggest this is a case of murder on the basis of wicked recklessness, [that the accused] did not care if Bailey lived or died."

Mr Prentice described the confrontation which led to Bailey's death as a "silly, trivial fight between two schoolboys".

He added: "This was a murderous attack because of the wicked recklessness of stabbing someone in the chest."

The Crown case concluded on Friday and defence counsel Ian Duguid QC confirmed the accused has elected not to give evidence.

He told the jury on Monday: "I'm suggesting this was a spontaneous event which happened in no more than 30 seconds.

"This was a single blow - the only blow that we know was landed on [Bailey]."

Mr Duguid described Bailey as the "aggressor" and told the jury he had advanced towards the accused before the stabbing.

He added: "This is not self-defence but this is provocation. Start with the consideration of what is the provocation and how much time [the accused] had to make the judgement.

"Seconds? Two, three, four? What is the time he had to decide the appropriate response. You must allow for the possibility that his response was a mistake."

Judge Lady Stacey urged the jury to find the accused guilty of possessing knives and knuckledusters in her closing remarks on Monday afternoon.

The trial previously heard the two boys rowed over a packet of biscuits before the stabbing.

In a police interview after the incident, the accused told police he had bought the knife to "act cool".