A teenager has been convicted over a stabbing which left a 17-year-old boy blind, paralysed and unable to speak.
Jamel Boyce went into cardiac arrest after being attacked with a knife in a "minor disagreement" in Clapham, south-west London on 14 October 2016.
He received first aid and was rushed to hospital but the loss of oxygen caused massive damage to his brain.
Tyrese Osei-Kofi, 18, of East Dulwich, was found guilty at the Old Bailey of wounding with intent.
He was found not guilty of attempted murder.
Det Con Sarah Mustoe, who led the investigation for the Met, said Jamel's future had been "cruelly torn from him".
The business student was at a McDonald's in Clapham High Street on the afternoon of the attack when there was a dispute with the people he was with.
'Like a pack of animals'
Four hours later, shoppers observed a scuffle near the car park of a supermarket and described seeing Jamel pinned up against a wall by Osei-Kofi, while others watched "like a pack of animals surrounding a buffalo", the court heard.
Osei-Kofi was heard shouting for a "chiv" (knife) whilst holding his right arm against Jamel's neck to trap him against some railings before stabbing him and leaving.
Paramedics and a trauma team who treated Jamel at the scene performed roadside surgery and managed to restart his heart before he was rushed to hospital.
'Severe and permanent' brain injury
The loss of oxygen to his brain for 14 minutes resulted brain damage, doctors concluded he lost 75-80% of brain function and is unlikely to make any significant recovery.
He was transferred to a specialist long-term care facility where he remains today and requires 24-hour care.
"His life was changed dramatically following those few seconds and his family's grief at losing the boy they cherished is immeasurable," Det Con Mustoe said.
Osei-Kofi handed himself into police on six days after the attack following media appeals in which his father recognised him.
He was subsequently re-arrested on 22 December and charged on 13 April 2017.
Sentencing is due to take place on 4 May.