Detectives have launched a murder investigation after a man died in hospital almost three weeks after sustaining serious head injuries.
On Saturday, 3 December police were called shortly before midnight to a south London hospital by a relative of a man that had been assaulted.
The victim had been attacked in the early hours of that morning in a communal stairwell of flats at 12 Vanguard Way in Wallington.
On Friday, 23 December, officers were informed that the victim had died in hospital. Next of kin have been informed.
He was 55-year-old Carl O'Brien.
A post-mortem examination will be held due course.
Detectives from the Homicide and Major Crime Command are now leading the investigation and are appealing for witnesses or anyone with information to contact them.
Detective Inspector John McQuade, said:
"Mr O'Brien was a very popular man, and his family and friends have now been left with the most tragic news just days before Christmas.
"I am appealing for any witnesses or anyone with any information regarding this murder to contact our incident room as a matter of urgency."
Anyone that can assist the investigation can contact the incident room on 020 8721 4054, or via the police non-emergency number 101.
To give information anonymously contact Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
A 26-year-old man has been arrested and charged with GBH in connection with this investigation.