At first the Metropolitan Police treated Mr Menson's horrific death as a suicide, and failed to take a statement from him as he lay dying in hospital.
But last night Deputy Assistant Commissioner John Grieve, head of the yard's Racial and Violent Crime Task Force, said he believed Mr Menson, the 30-year-old son of a Ghanaian diplomat, was the victim of a racially motivated attack.
``Race crime is hate crime,'' he said. ``Someone knows who killed Michael Menson, and we appeal for any outstanding witnesses to come forward.''
DAC Grieve now believes three to four people were involved and some have boasted about it to friends around Edmonton, north London. He said several witnesses had been trying to contact the police. Detectives have several suspects and some new lines of inquiry have opened up recently.
Just under two years ago Mr Menson, who suffered from depression and schizophrenia, was found wandering naked, in flames, near the North Circular Road in Edmonton. He died two weeks later in Billericay Hospital, Essex.
Since then, Scotland Yard has confessed to making serious mistakes in the way it investigated the death. The Police Complaints Authority has begun an inquiry, and an inquest last September returned a verdict of unlawful killing.
Witnesses have contacted the police to tell them that on the bus route Mr Menson used on the night of the attack, there had been racist talk about burning people.