A 15-year-old boy who tracked down a teenager he didn’t know through Birmingham city centre and fatally stabbed him after a brief four-minute exchange has been sentenced to life imprisonment with a minimum of 13 years.

Muhammad Hassam Ali, known as Ali, was 17 when he died in hospital on January 20, shortly after he and a friend were approached by two masked 15-year-olds they had never met while sitting in Victoria Square, enjoying hot chocolate and discussing cricket.

The boys, whose identities remain protected, had followed Ali and his friend from the Grand Central Shopping Centre, wearing Covid-style masks. Neither showed any reaction as Judge Justice Garnham at Birmingham Crown Court delivered the life sentence, calling Ali's murder "another tragic consequence of carrying knives in public.”

He said: “It is perfectly clear to me (Ali) was a much-loved son and brother and his family have been left utterly devastated by his death.”

He sentenced the second boy to five years’ detention in secure accommodation.

A trial at Coventry crown court earlier this year heard that, in a conversation lasting about four minutes, the two boys asked Ali and his friend where they came from and if they knew who had “jumped a mate” of theirs a week before. After Ali allegedly said: “Bro, I don’t know what you’re talking about, you’re pissing me off,” the youth pulled out a large knife and stabbed him in the chest.

A jury took just over four hours to return unanimous verdicts in July, finding the youth who carried out the fatal attack guilty of murder and possessing a knife and his friend, who was standing nearby when the stabbing happened, guilty of manslaughter and possessing a knife.

In his evidence, the teenager who wielded the knife told the court he only wanted to “scare” Ali and his friend, and that he did not intend to seriously harm or kill anyone.

Michael Ivers KC, representing the defendant, said he was remorseful and prays for Ali and his family regularly.

He said: “He isn’t a man who is in any sense proud of what happened. He truly, truly regrets what happened.

“If he could turn the clock back, not for his own sake but because of the impact it has had on others, he would.”

Sentencing the pair, who sat in the dock wearing white untucked shirts and dark trousers surrounded by four dock officers, Mr Justice Garnham said the knife had been pulled out “for no obvious reason”.

He said: “You suggested in evidence that the words of Ali caused you to fear for your safety. The jury did not accept that and neither do I.

“They did no more than was reasonable in trying to persuade you to go away. There was no justification for pulling out a knife on an unarmed young man who posed no risk to you.”

A statement from Ali’s family, who were in court for the hearing, read out by prosecutor Mark Heywood KC described the teenager as a budding engineer and said they would never get over his death.

They said: “The loss of a child is devastating and life-destroying, but the fact someone took his life in such a horrific and brutal way will always haunt us.”