The beaten and burnt body was found face down in a park
The identity of the murdered boy, who was Asian and aged between 12 and 15, has not yet been established despite a nationwide appeal through the Missing Persons Bureau.
Detectives are checking with schools in the area and all reports of missing children are being followed up.
The murder has shocked the local community in Kingsbury.
Shaken confidence
The boy was set on fire with petrol, but no attempt was made to hide the body which was found in Roe Green Park in Kingsbury.
The police believe the child suffered serious head injuries.
An expert is trying to produce a computer-enhanced image of the victim which can be released to the public.
People living near Roe Green Park, Kingsbury, said they were "extremely disturbed" by the killing.
Deeva Samaroo, a community leader, said inter-ethnic community relations were very good, but this had shaken peoples' confidence.
Mr Samaroo said: "From my telephone calls to other community leaders they are also getting extremely worried that no-one has yet come forward to identify the child."
Police are carrying out house-to-house inquiries and examining CCTV footage from the area.
Reg Colwill, Tory councillor for Kingsbury, said people in the borough were frightened to go out on the streets.