A man murdered in Pilgrimage Street last Friday has now been formally identified as David Maxwell, aged 18, of Borough Road.
The teenager died from stab wounds outside the Quality Food Store in Pilgrimage Street on Friday afternoon.
A 20-year-old man was arrested on suspicion of murder on Monday and remains in custody at a south London police station.
An 18-year-old from Southwark was arrested on Saturday on suspicion of perverting the course of justice. He was subsequently released on bail.
Any witnesses or anyone with any information is asked to call the incident room on 020 8721 4961, or police via 101, or Crimestoppers anonymously on 0800 555 111.