Nathaniel Eyewu-Ago, 35, was in a critical condition in hospital after he was stabbed in a knife fight on Wednesday, June 2.
Police found him with knife wounds in Barge Walk at 4.23pm after being called to reports of men fighting.
He was rushed to hospital but died on Tuesday, six days later. A 17-year-old man, a 22-year-old man and 25-year-old man were arrested on suspicion of murder on Tuesday, while a 43-year-old man was was also arrested in the early hours of Wednesday.
Detective Chief Inspector Kate Kieran, who is leading the investigation, said: “The victim in this case suffered the injuries that would ultimately claim his life in broad daylight, outside a residential address.
“These arrests mark significant progress in the investigation and I hope it reassures the community that officers are working hard to bring justice to the victim and his family.
“This is now a homicide investigation. I am still keen to hear from anyone who witnessed the incident or who may have dash cam footage of the stabbing itself or the events surrounding it. If you can help please don’t hesitate, call us direct or remain anonymous, but either way please do make the call.”
The four men remain in custody at police stations in south London.
Mr Eyewu-Ago’s next of kin are aware and are being supported by specialist officers.
Any witnesses or anyone with any information should call police on 101 or Tweet @MetCC quoting CAD 5308/02JUN. To remain 100% anonymous contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.