Detectives investigating the murder of Christopher Foster in Borough High Street a week ago made a second arrest on Friday.
A 30-year-old man was arrested on suspicion of murder at around midday on Friday and was taken into custody at a south London police station.
Officers are continuing to appeal for information about the fatal stabbing which took place late on the night of Friday 30 November.
On Friday night – a week after the murder – detectives handed out appeal leaflets in Borough High Street in the hope of tracing further witnesses.
Anyone with information that may assist the investigation should call the incident room on 020 8345 3865 or call Crimestoppers anonymously on 0800 555 111.
On Sunday 1 December a 32-year-old woman was arrested on suspicion of assisting an offender. She was taken to an east London police station and later released on bail.