Moments after the teenagers were captured running after him and a friend, Kwame was stabbed 14 times in the back in a 'cowardly and merciless' murder.
The pair were members of the TN1 gang - Trust No One - out to avenge one of their numbers who was stabbed by a rival gang member from the GAS gang - Guns and Shanks - just hours earlier.
His killers had toured housing estates in Brixton to find rival gang members and came upon the 17-year-old son of a sports broadcast journalist and his friend, who had nothing to do with any gangs.
Nathaniel Okusanya, left, Nelson Idiabeta, rightKwame, a business student, promising footballer, a budding actor and rapper, was walking back with a friend from a session at a recording studio when they were confronted by Okusanya and Idiabeta in the Moorlands Estate in Brixton.
Kwame and his friend with a 'sixth sense' ran away into a cul de sac where his friend’s aunt lived in a desperate attempt to get to safety - but she was not at home.
His friend managed to jump over a wall but Kwame was trapped and then killed on March 2 of this year.
He shouted out he was from Catford and pleaded 'I’m not from round here, I’m not from round here' but he was murdered by the pair who had persuaded a shopper to buy them at least one substantial kitchen knife just hours before the attack.
After an Old Bailey jury found the pair guilty Nelson Idiabeta, now 18 was jailed for a minimum of 19 years while Nathaniel Okusanya, 19, was jailed for 20 years.
Sentencing Judge Richard Marks QC said: 'I am entirely satisfied having heard the evidence the background to this terrible offence is to be found in revenge between two gangs.
'Around 1.15pm Garfield Stewart a member of TN1 gang was stabbed 28 times while sitting in a bus while it was stationary at West Norwood.
When the shopkeeper refused to sell them the weapon without seeing a passport or driving licence they asked a stranger to help, claiming one of their mothers needed it for cooking.
The pair then got a taxi driver to take them to Brixton and drop them off at the edge of the Moorlands Estate at 5.30pm.
At that time Kwame, who lived in Catford, happened to be walking through the estate with one of his friends after leaving the recording studio.