Ian Kirwan, 53, had challenged a group of youths for ‘messing about in the toilets’ of an Asda supermarket in Redditch, Worcestershire, on March 8 last year.
Mr Kirwan, a Jaguar Land Rover employee, was stabbed in the heart outside the Jinnah Road store and died within an hour.
Today a jury at Birmingham Crown Court found the boy who stabbed Mr Kirwan – who is now 15 but was 14 at the time – guilty of murder and possession of a knife.
Police have now released CCTV footage showing the teenagers in the ASDA moments before Mr Kirwan was killed.
A 16-year-old boy, who was 15 at the time, was cleared of murder and an alternative charge of manslaughter but found guilty of violent disorder. He had previously admitted to having a knife in his possession.
Two 14-year-old boys were also found guilty of violent disorder after being cleared of murder and manslaughter. Another 16-year-old boy was acquitted after being cleared of murder, manslaughter, and violent disorder.
The jury deliberated for more than 30 hours. Sentencing plans have yet to be finalized.
Mr Kirwan, a ‘loving uncle’ to three nephews, worked as an artificial intelligence engineer for Jaguar Land Rover, first in Coventry and then from home after the Covid-19 pandemic.
On March 8, last year, he went to B&Q in Redditch to get a replacement light switch before going to Asda to get some wine and snacks.
He first encountered the boys, who had entered the store with their hoods up and faces covered, while using a toilet in the supermarket around 7:15pm.
One of them boasted about urinating on the floor during the trial, while another banged on Mr Kirwan’s cubicle door to get him to hurry up.
Mr Kirwan approached the group as they sat on trollies outside and asked, ‘Which one of you was f***ing around in the toilet?’
One of the boys allegedly replied, ‘If you want a problem, we’ll have a problem.’
The court heard that a scuffle followed. Mr Kirwan was confronted by a group of youths who made karate-style defensive kicks, as captured on CCTV.
At 7:19pm the 14-year-old delivered the single fatal blow to his chest with the knife. Mr Kirwan retreated inside the supermarket but died less than an hour later before making it to hospital.
The youths, one of whom briefly pursued the victim into the store, fled the area towards Redditch railway station.
A ten-week trial at Birmingham Crown Court was told Mr Kirwan, an artificial intelligence engineer who worked at Jaguar Land Rover’s Coventry headquarters, was an ‘unfortunate member of the public in the wrong place at the wrong time’.
All those convicted will be sentenced, at the same court, on February 15.
High Court Judge Mr Justice Fraser told the 15-year-old who was convicted of murder: ‘I know that your counsel will have explained this to you already – you are going to be sentenced to the youth equivalent of a life sentence.
‘But I am not going to pass that sentence (now) because I have to fix the minimum term. That is something I intend to do on February 15th.
‘On February 15, you will be physically brought to court.’
The adolescent, who appeared via video link from a secure unit, showed no reaction as the jury returned its guilty verdict, glancing to his left and then at a floor before continuing to watch other verdicts being read.
Following the verdict, Mr Kirwan’s widow stated, ‘The decisions made by the youths on March 8, 2022, not only took my husband from me, but it also took my life, my plans for the future, and has an impact on all my choices I make in life.
‘Normally when a person dies, they are surrounded by loved ones and family but because of the tragic circumstances of Ian’s death, he died alone surrounded by strangers who were kind enough to help him.
‘Nobody should ever have to die like that.’
Detective Superintendent Leighton Harding, senior investigating officer for West Mercia Police, said: ‘This was an appalling attack on an innocent man going about his daily life, which caused shock and upset in the local community.
‘I’m pleased that justice has been done today for Ian and our thoughts remain with his family and friends, who have shown incredible strength throughout the investigation and the trial.
‘I’d like to take this opportunity to thank the public for their assistance in identifying witnesses who were critical to this investigation. We received an overwhelming response to our appeals, and the information gathered was critical in securing this conviction.
‘I’d also like to thank the team who worked on this case. It has been an extremely complex investigation, and they have worked tirelessly to ensure Ian’s justice.
‘The danger of carrying a knife is painfully obvious in this very sad case. It is simply unacceptable for anyone to carry a knife.
‘Thankfully, violent behaviour on the streets in our area is a rare occurrence but we continue to work hard to keep our communities safe. Today’s convictions send a clear message that we will take swift action against anyone who carries a knife or engages in violence.’