A 16-year-old girl left in a coma after an attack more than four months ago has died.
Julie Sheriff had been fighting for life since May after being hit in the head during an attack in Battersea, south-west London.
A 15-year-old girl appeared at Balham Youth Court in May accused of assault in relation to the attack.
Detective Chief Inspector Nick Scola, of the Metropolitan Police, said: "Our thoughts are with Julie's family at this difficult time."
The girl, from Hackney, east London, had been visiting friends when she was attacked in the street.
After her death on Wednesday last week, a post-mortem examination on Friday gave cause of death as head injuries with associated complications.
The case has been passed to Scotland Yard's Homicide and Serious Crime Command squad in Sutton.
Mr Scola, who is leading the investigation, said: "We know from CCTV that some of the witnesses have not yet come forward and since the tragic death of this young woman, we urge them to do so.
"We would like to appeal to the public to think back to the time of this assault and speak to police as soon as possible.
"Julie was visiting friends in the Battersea area at the time. If you know anything about what happened on May 7 I urge you to contact the incident room."
