A 19-year-old man has been charged with the murder of Hani Hicham Abou El-Kheir, the teenager stabbed to death in Pimlico, central London, on 27 January.
Ahmed Mikhaimar, of nearby Vauxhall Bridge Road, was charged with the 16-year-old's murder yesterday evening.
Mikhaimar has been remanded in custody and will appear at Redbridge magistrates' court this morning.
Officers were called to the murder scene at Lupus Street after Hani had been attacked by a gang wielding knives and swords. The victim was taken to hospital in south London but died from his injuries.
Witnesses said Hani had begged for his life but was stabbed repeatedly by the gang, which is believed to have consisted of around 15 teenagers.
One eyewitness told the Evening Standard: "We were walking along and saw him running really fast but then he tripped. There were about 15 of them, most wearing dark hoodies and bandanas over their faces. A lot of them were wearing tracksuits.
"They had wide kitchen knives and other knives and they jumped on him like a pack of dogs.
"He was shouting 'don't do it' but they just went ahead. One put a blade in near his ribs. Others then kicked him before just jogging off as if nothing had happened.
"They put their weapons in socks and then shoved them up their sleeves as they were going.
"Afterwards they looked calm, one looked straight at me as he was leaving which was scary - we thought they may go for us. We tried to help him as he was lying on the ground."
Hani was known to anti-drugs workers in the area but was on the periphery and was not thought to be a gang member.
David Savizon, from the anti-drugs group Your Choice, said: "Unfortunately, I wasn't able to meet him. He wasn't deemed significant in terms of being in a gang. He was mentioned as someone on the periphery."