
Teenager Jailed for Minimum 17 Years Over John McNab Knife Murder in Leith
A teenager has been handed a life sentence, with a minimum term of 17 years, for the murder of John McNab in Leith. The 17-year-old, who cannot be named due to his age, pursued and fatally stabbed 22-year-old McNab on Great Junction Street on 2 September last year.
Bail Preceded Fatal Attack
The lethal assault took place four months after the youth had been released on bail, following charges for a knife attack on a 16-year-old at Portobello Beach. The teenager previously admitted guilt for both incidents.
During sentencing at the High Court in Dundee, Lord Harrower, the presiding judge, condemned the “merciless attack” that ended a young man’s life, leaving an “incalculable void” for his family and friends.
CCTV footage presented in court showed warehouse worker McNab pleading for his life before the teenager stabbed him four times as he lay on the ground. McNab’s mother, Lisa Petrie, described the footage as haunting, stating, “Imagine how scared he was in that moment. That’ll be with me for the rest of my life.”
Victim Uninvolved in Prior Altercation
On the night of the murder, some of McNab’s friends had a brief altercation with the teenager. The youth followed them, issued threats, and waited for over two hours before targeting McNab, who was leaving to get a taxi and had not been involved in the earlier incident. McNab’s pleas of “Please, please don’t. I haven’t done anything” were captured on CCTV before he was fatally stabbed.
Following the murder, the teenager sent threatening voice notes to one of McNab’s friends, stating, “Let that be a warning to all your pals if you ever touch me again.”
Mother Campaigns for Knife Law Reform
Lisa Petrie, McNab’s mother, expressed profound distress at seeing the hunting knife used to kill her son, which featured a 20cm blade. She has since initiated a campaign for stricter regulations on the sale of kitchen knives, suggesting they be secured like spirits or kept behind counters. Petrie also advocates for tighter controls on the sale of blades like the one used in her son’s murder, questioning why the perpetrator was granted bail after the earlier knife attack, arguing he should have been held in a secure unit.
Mark Stewart KC, defending, stated that the teenager acknowledged the harm caused. He added that the youth had no prior convictions, handed himself in after both attacks, and has since been diagnosed with autism and post-traumatic stress disorder. The teenager will remain detained indefinitely, with release contingent upon a parole board assessment of public safety.

