Police are investigating after a boy who admitted killing his friend took a video of himself in a toilet during his murder trial making stabbing actions.
The 17-year-old boy, known only as Boy A, admitted stabbing Yousef Makki in the heart but said it was self-defence.
He was cleared of murder and manslaughter at Manchester Crown Court.
It has emerged that the teenager recorded a video during the trial and it was later sent by someone to Yousef’s family.
In the video, which has been seen by the BBC, the boy – who was granted bail during the trial – appears to be in a toilet cubicle and starts making stabbing motions while listening to drill music about “blades” and “shanks”.
The date on the video is 4 July – the day he gave evidence in the trial – but it is thought it was published at a later date and then sent by someone to the victim’s distraught family.
Detectives are investigating whether an offence has been committed under the Malicious Communications Act by whoever sent it to the Makki family.
Yousef was stabbed in Hale Barns, Greater Manchester, on 2 March.
When police arrived, Boy A falsely suggested that Yousef had been stabbed by someone who drove off in a grey VW Polo, information which was circulated on the police network.
His convincing lies, the judge said, meant he was treated as a witness not a suspect and undoubtedly wasted valuable police resources.
Boy A admitted perverting the course of justice and possession of a knife and is serving eight months in custody.
In an interview with the BBC after the trial, Yousef’s sister Jade Akoum, 28, said she had sent the video to the trial judge.
She said she believed it had been taken on the day the defendant gave evidence, adding: “He was sat in the toilets of the court and there was drill/rap music in the background about knives and he was mimicking stabbing.”
On Friday she told the BBC the video was “just shocking and showing lack of remorse and respect to us as Yousef’s family”.
Matthew Claughton, of Olliers solicitors which represented Boy A, confirmed to the BBC the video was his client and Olliers had made representations about it to the trial judge.
Mr Claughton said he had nothing to add to a statement made to a newspaper on Thursday in which he said the video “reflected his (client’s) frustration with the way the prosecution were misrepresenting videos that were played at court”.
He said it was “worth remembering that the jury appear to have agreed with that view given the not guilty verdicts”.
Greater Manchester Police said: “Officers are investigating a video which has been circulated in relation to the Yousef Makki murder trial.”
As he sentenced Boy A Mr Justice Bryan said the boy “found knives cool” and that he videoed himself with them.
“You also listened to drill music and gangster rap glorifying the carrying and use of knives.”
Another 17-year-old, known as Boy B, was given a four-month detention and training order after he also admitted possessing a knife.
Yousef, from an Anglo-Lebanese family, had won a scholarship to the prestigious £12,000-a-year Manchester Grammar School and his father said his son had dreamed of becoming a heart surgeon.
The trial heard the stabbing in the village, which is popular with footballers and celebrities, was an “accident waiting to happen” as all three teenagers had indulged in “idiotic fantasies” playing middle-class gangsters.