He was hunted down by youths on bikes near his parents’ home in Islington, north London, on August 24, 2017, and stabbed with a Rambo knife.
Stuart Miller Solicitors was enlisted to represent Mr B – one of two co-defendants accused of murder.
Mr B was alleged to have “summoned the troops” after chasing the victim on his bike.
He was then stabbed after running into the path of another man, who brandished the lethal weapon.
Mr B was charged with murder under the law of joint enterprise – which can result in people being convicted of a crime even if they did not directly commit it.
A spokesman for Stuart Miller Solicitors said: “The murder itself was shown on CCTV of good quality and the knife and the stabbing was caught clearly by a neighbour who captured a short part of the incident on her mobile phone.
“Witnesses from a short distance away also gave their accounts during the trial.
“Stuart Miller Solicitors examined the lengthy CCTV footage in an attempt to distance our client from the male described as causing the deceased to run back towards the ‘stabber’.”
Prosecutors also wanted to show jurors a music video featuring Mr B and other members of the Islington gang ‘Cally Boyz’ in which they brandished knives.
The spokesman said: ““ The Crown wanted to show that they all had a propensity to carry knives.
“The visuals were overlaid with lyrics directed at rival gangs in what prosecutors said was a bid to coax them into ‘tit for tat’ violence.
“The defence successfully applied for the majority of the video to be excluded during the trial on the basis that it would be more prejudicial than probative.”