The family of a private school pupil who was fatally stabbed have spoken of their devastation and said they will “take legal steps” after a teenager was found not guilty of his murder.

A 17-year-old boy, who cannot be named, had been accused of killing his friend Yousef Makki, 17, during an argument in an affluent suburb of Cheshire.

But on Friday the teenager, known only as Boy A, was found not guilty of both murder and manslaughter following a trial at Manchester crown court.

Speaking for the first time since the verdicts, Makki’s family said on Monday that their grief had been compounded by the acquittal and that they would be “taking legal steps” to challenge it.

Makki’s elder sister, Jade Akoum, said: “We as Yousef’s family are absolutely devastated by the verdict given on Friday. We have suffered heartbreaking losses twice now, firstly in losing Yousef and secondly now that no one has been found accountable of his murder.

“This has affected us all immensely, not just our family but every one in the community too. All we wanted was justice for Yousef and closure. It feels now that we have not achieved that.”

Makki, who came from an Anglo-Lebanese family and lived in Burnage, dreamed of becoming a heart surgeon and had won a scholarship to attend the prestigious Manchester Grammar school.

The trial heard that the teenager was stabbed in the heart with a flick knife after getting into an argument with his friends in the upmarket Cheshire village of Hale Barns, a suburb popular with footballers and television stars.

On 2 March, Makki was with the two defendants when they made a botched attempt to buy £45 worth of cannabis on a farm track. Boy A was attacked and had his bicycle thrown over a hedge.

Boy A then later pushed Makki, who called him a “pussy” and punched him in the face, the court heard. The defendant told the jury Makki pulled out a knife and he responded by also taking out a knife, then accidentally stabbed his friend.

Boy A then got rid of the knives in a panic before realising how serious the injury was and started to try to staunch the blood pouring from his wounded friend’s chest as he lay dying in the street.

Makki’s father, Ghaleb Makki, collapsed in court following the not guilty verdicts, which prompted shouting and tears from the victim’s family and emotional scenes as Boy A walked free from the dock into the arms of his relatives.

Akoum, 28, on Monday described her brother as a “caring and loving brother, son and uncle” and “an incredibly bright and ambitious person” who had achieved all A grades in his GCSEs the year before his death. She said he was a “loyal and loving friend” who would “go above and beyond to support his friends in difficult times and had a kind and humble nature”.

Akoum, a mother of three, said: “We understand the country is as upset as the rest of us on the verdict and we will of course be taking steps legally to ensure Yousef’s life did not end in vain.”

At a family event in Stockport, Akoum thanked teachers at Manchester Grammar school for their support and thanked her brother’s friends “for upholding Yousef’s memory with dignity”.

“Yousef was so lucky to have had you all as friends. All the letters, emails and messages from the public, we all really appreciate your kindness,” she said.

Boy A denied murder, claiming that he acted in self-defence because Makki had pulled out a knife. He admitted possession of a flick knife and perverting the course of justice by lying to police.

A second 17-year-old, Boy B, was cleared of lying to police about what he had seen but admitted possession of a flick knife. Both were cleared of conspiracy to commit robbery before Makki’s death.

In a statement, Boy A’s family said on Friday they welcomed the verdicts and that the jury had come “to a proper conclusion on the evidence”. They added: “There are, however, no winners in this case. Yousef’s death was a tragedy and our son will have to live with his responsibility of his role for the rest of his life.

“But the Makki family’s hurt and loss are infinitely greater. Nothing we can say can make up for that or change it.”

• This article was edited on 23 August 2019 to amend details relating to Boy B.

