CCTV images released today show the moment before an innocent teenager is murdered, because his killers mistakenly thought he was a member of a rival gang.
Kwame Ofosu-Asare wasn't.
But he was stabbed to death on a housing estate in Brixton.
Today his killers were jailed for life.
Some of you may be upset by some of the images in this report by Piers Hopkirk.