The death of schoolboy Bailey Gwynne might have been avoided if those who knew his killer carried weapons had reported it to staff, an independent review has concluded.
The multi-agency probe into the stabbing of the 16-year-old at Cults Academy in Aberdeen has made a series of recommendations, including calling on the Scottish Government to consider changing the law to give teachers more power to search pupils.
Bailey's killer, a 16-year-old youth who cannot be named due to his age, was locked up for nine years in April after a jury found him guilty of culpable homicide and carrying weapons.
The review, led by child protection expert Andrew Lowe, concluded the fight that took place during the school lunch hour on October 28 last year could not have been predicted or averted on the day.
But it found the course of the conflict was "fatally altered" by the fact the killer had a knife, which could have been avoided if others who knew this had reported it to staff.
During a five-day trial at the High Court in Aberdeen, a friend of the boy said he had shown him a knife and knuckledusters he had in his possession on several occasions from the end of 2014.
The review's conclusions state: "This was an unplanned, spontaneous conflict that emerged rapidly out of an unexceptional banter. It is not considered that it could have been predicted or averted on the day.
"The course of the conflict was fatally altered by the possession of a bladed weapon by one of the boys.
"This was potentially predictable and avoidable if those who knew Child A carried weapons in school had reported it to staff."
Currently in Scottish schools, pupils have to give their consent to be searched, with police notified if consent is withheld and a child or young person is suspected of carrying a weapon.
The review recommends the Scottish Government "should improve the resilience of schools to the threat posed by weapons and give consideration to amending the law in relation to searching pupils".
The trial also heard the knife used in the stabbing had been bought online, without the killer having to prove his age.
"The Scottish Government should explore the further legislative controls that can be brought to bear on the purchase of weapons online," the review states.
It recommends that Aberdeen City Council works with Police Scotland to draw up a "clear and effective" policy on the management of offensive weapons in schools, and that pupil forums and councils develop "safe" ways to allow young people to share any knowledge of weapons with teachers.
The probe also calls for individual risk assessments for anyone "known or suspected to carry offensive weapons" and "age appropriate" training for P7, S1 and S5 pupils on knife crime.
The review concluded that the incident had been "well-managed" by all the agencies involved.
Speaking at a press conference in Aberdeen, Mr Lowe said the incident happened very quickly.
He said: "It's important to understand the rapidity of this event because it all took place in less than five minutes from the meeting of the boys to the intervention of the teacher.
He added that "several children" had been aware the killer carried weapons, and he called on pupils to act responsibly.
"Children and young people must be the key to the solution to knife crime in schools," he said. "Rights should always be balanced with obligations."
He pressed the need for processes to allow pupils to share any knowledge of weapons safely with school staff.
Mr Lowe said: "This was a critical matter in these events.
"We know as adults how we are nervous about disclosing information, clyping on friends, particularly if we don't think that friend has malign intent but is just showing off a little bit.
"We can't afford to have that belief in our children and in our schools, we must be vigilant and they must be vigilant."
Mr Lowe also said he had considered an incident in 2007 which Child A was involved in when he was aged eight, but said that had "marginal significance" in relation to later events.
He said it "did not reveal a violent child but a child under very significant and continual pressure from his brother."
Mr Lowe conducted 42 interviews in the course of preparing his 17,000-word report.
Mr Lowe said he had held a private meeting with Bailey's family on Monday, adding: "They demonstrated their remarkable dignity, as they have every time I've met them."
In a question and answer session with the press, he acknowledged that on one occasion before the fatal stabbing the school's headteacher was alerted that the boy was carrying a weapon on a bus - but after a search nothing was found and he concluded she had acted "swiftly and appropriately".
Asked why he thought some pupils felt they could not report that they were aware of weapons being brought to school, he said: "I don't know whether they didn't feel able or whether they didn't feel it necessary.
"This wasn't a boy who they perceived to be violent or conducting risky behaviour. This was a quiet boy and his motivation for carrying weapons was understood by some of these boys as just a form of bravado."
On the need to give senior school staff more powers, he added: "I don't think the law as it currently stands gives sufficient support to teachers in these circumstances.
"Establishing consent (to be searched) in these circumstances can be difficult, it isn't always forthcoming, there is a duty of care to the other pupils in the class, there is an expectation to keep everyone safe, there is an expectation that they deal with many things, and frankly the law doesn't support that."
But he said he does not believe bouncers or metal detectors at the school gates is the answer.
Police Scotland Chief Superintendent Campbell Thomson told the briefing that since November 2015 to the end of August, there had been 15 reports of knives in schools in Aberdeen.
Mr Thomson said each incident had been "robustly investigated" and he emphasised a range of explanations, such as a knife being taken into school for an art class, to the potential that others were being used for self-harm.
Mr Lowe said he is frustrated that the full review report has not yet been published due to legal and data protection issues.
Angela Scott, chief executive of Aberdeen City Council, insisted it would be published once all the proper permissions had been sought from those who took part in the review.