A man died following a stabbing incident at a house in an affluent part of south London.
Police were called to an address in Drakefield Road, Tooting – where properties are valued at around £1m ($1.24m) – at 3am on Saturday, 21 January.
The man, believed to be his 20s, is yet to be identified. He was given first aid, but died from his stabbing injuries shortly after being taken to hospital.
A 29-year-old man – who also suffered stabbing injuries – was arrested on suspicion of murder and remains in custody after being discharged from hospital.
A Metropolitan Police spokesman told the Evening Standard: "Enquiries continue to establish the man's identity. Next of kin are yet to be informed. A post-mortem examination will be arranged in due course."
Police said a 17-year-old girl was also taken to hospital after being stabbed in the hands, but she is not in a life-threatening condition.
All three people are said to have known each other.