Two 17-year-old boys have now been arrested after Alex Scott was stabbed to death in Eltham Road, Lee, following an apparent row over a cigarette.
Emergency services were called at 9.46pm on Sunday (August 10) to reports of a 26-year-old man suffering stab wounds.
The victim, named locally as Alex Scott, had suffered stab wounds to his chest and was pronounced dead at the scene.
As reported yesterday, according to residents the attack happened after Mr Scott argued with two men over being given a cigarette.
He was then chased through Leegate Shopping Centre and stabbed just outside it.
A post-mortem examination gave the cause of death as hemorrhage and stab wounds to the heart and aorta.
Yesterday (August 11), police arrested a 17-year-old boy on suspicion of murder. He was taken to a south London police station for questioning and remains in custody.
Another 17-year-old boy was arrested today.
Anyone with information on the murder is asked to call the Met's incident room on 020 8721 4005 or Crimestoppers on 0800 555 111.