The family of an Anglo-Lebanese stabbing victim have called for a retrial on the first anniversary of his death.
Yousef Makki, 17, was killed after a fight with his friend Joshua Molnar, 18, in the upmarket Hale Barns area of Greater Manchester last March.
Following a trial last year, Molnar was acquitted of murder and manslaughter but was locked up for 16 months for possessing a knife and perverting the course of justice.
He was released early last week.
Now, Mr Makki's family have called for a retrial.
At a press conference, his sister Jade Akoum said they had been told of Molnar's release last week.
"Police told us on the morning of the release – we were getting mentally prepared for his release later on in March," she said.
"If we can’t have a retrial, we will be launching a civil case.
"The justice system completely failed normal, average families at every step that we have taken so far, and I think things need to change.
"A lot of the evidence was not put forward in the right way."
Molnar claimed that he acted in self-defence.
Another teenager, Adam Chowdhary, then also 17, was acquitted of perverting the course of justice but given a four-month detention order after admitting to the possession of a flick knife.
Mr Makki's family have criticised the investigation into his death, which was carried out by Cheshire Police and Greater Manchester Police.
At present, both forces are being investigated by the Independent Office for Police Conduct in relation to the case.
Under UK law a person can only be retried if new evidence comes to light.
Mr Makki was a bright student studying at the prestigious Manchester Grammar School when he died on March 2 last year. He suffered a stab wound to the heart.
Mr Makki had grown up on a social housing estate and won a scholarship to attend the £13,000 (Dh61,000)-a-year school.
His family have claimed class played a role in the verdict as both the accused came from privileged backgrounds.
Last year following the verdict, Mrs Akoum said: "We all thought the trial we would get closure and at least the truth. We didn't even get truth."
It is claimed the stabbing took place over a failed attempt to rob a drug dealer of £45 worth of cannabis.
Mr Makki had been preparing to apply for university at the time of his death and had ambitions to become a surgeon.