A 16-year-old smiling killer was given a life sentence for stabbing schoolboy David Idowu to death.
David, 14, died on July 7 last year, three weeks after being stabbed in the chest at a football pitch in a local park.
Elijah Dayoni, 16, was found guilty of murder last month and has now been ordered to be detained during Her Majesty's Pleasure, serving a minimum of 12 years.
Old Bailey judge Mr Justice Calvert-Smith lifted a ban on naming Dayoni, of Catford, south east London.
He said David was a model student and son while Dayoni had been under a supervision order at the time and had committed a burglary the day before the killing in Southwark, south London, on June 17.
Police said the 16-year-old approached him without warning and stabbed him in the heart.
As David tried to escape, the attacker chased him. The 16-year-old was caught on CCTV laughing and smiling.
David collapsed on Beckett Street where passers-by helped to keep his heart going, but it stopped twice.
He was flown to the Royal London Hospital by air ambulance but never came out of his coma.
The court heard the 16-year-old was arrested two days later still wearing a T-shirt with David's blood on it.
