A teenager who stabbed a man to death over a comment about a "fit" girl has been jailed for 14 years.
Haris Mohammed, 16, knifed Tom Webb, 22, in the chest in a "cowardly and senseless" attack in Derby city centre.
He remained unemotional in the dock at Nottingham Crown Court today as he was sentenced for killing refuse worker.
During the trial, the jury heard that Mr Webb was with two friends in the city centre buying food and drink at Tesco on the fateful evening.
As they left the store he had made a remark about a young woman who was walking past being "fit."
The jury heard that one of Mohammed's friends overheard the comment and told him about it.
He then used a butterfly knife with a blade about seven centimetres long to stab Mr Webb - yet he told the trial it was in self-defence.
Since his death, Tom's mother Rachel Webb, has spoken if her 'indescribable pain" at losing her only child, who she said planned to join the Navy.
Ordering Mohammed to be detained at Her Majesty's pleasure - the juvenile equivalent of a life sentence, Mrs Justice Cox told him today: "The victim personal statements (from Mr Webb's mother and his fiancee) describe in poignant and moving detail the extent of their grief.
"The fact that you were carrying in a public place, and at night, the knife which you then used in the fatal attack is without doubt a serious aggravating feature in this case.
"You could so easily have turned and walked away."
Mohammed, of Allenton, Derby, was convicted of murder by a jury a fortnight ago after four hours of deliberations.
During her sentencing remarks, Mrs Justice Cox told the teenage killer: "It is clear that you continue to assert that which you told the jury - that you were trying to defend yourself.
"You most certainly were not.
"Tom Webb was out in the town with his two best friends.
"They were not looking for trouble and had caused no trouble for anyone at any stage.
"They posed no threat to you whatsoever. I reject entirely the suggestion that you felt yourself to be under threat from Tom."
Before sentence was handed down, the victim's mother, Rachel Webb, spoke at length in the witness box about her only child, who planned to join the Navy.
After thanking the judge for the opportunity to address the court, Ms Webb, who suffers from post-traumatic stress, said: "Tom was a warm, kind, thoughtful and loved son, who had just started out on his life journey.
"Tom will never have a future and the pain this causes me is indescribable."
The court heard Mohammed took six GCSEs and other courses while on remand.
Offering mitigation for the teenager, defence barrister Peter Joyce QC told the court: "He has started to understand the depth of the harm that he has done and to seek to improve himself."
Reporting restrictions banning the identification of Mohammed were lifted at an earlier hearin
Detective Chief Inspector Dave Cox, who led the investigation said: "I hope that this sentence sends a strong message to anyone who is thinking of carrying a knife.
"Carrying a knife can have serious consequences and this is proof of that.
"A young man lost his life that night and another youngster will now be spending at least 14 years behind bars."