Danielle Johnson was attacked on the last bank holiday

Danielle Johnson, 17, was attacked in Wood Green, north London, at the rear of Wendover House in Palmerston Road, on 28 May.

A post-mortem examination gave the cause of death as a stab wound to the chest and head injuries.

A 17-year-old boy, arrested on 30 May, has been charged with attempted murder in connection with incident.

Det Ch Insp John Macdonald said: "We are appealing for witnesses to come forward after this terrible attack.

"Given that this happened on a bank holiday and in daylight we hope that there will have been people in the area who may have seen somebody acting suspiciously or heard something that may be vital to our enquiry."