The family of Kester David, 53, whose body was discovered with 100 per cent burns in July 2010, launched legal action against Scotland Yard alleging that detectives had failed to investigate the case properly because the victim was black.
An initial investigation concluded that Mr David, who was from Wood Green, North London, had taken his own life.
But a coroner returned a verdict of open death and a forensic expert said that he could not rule out the possibility that a third party was involved in Mr David's death.
A leaked report into the case later revealed a series of errors in the original inquiry and Mr David's family launched legal action against Scotland Yard, calling for an independent investigation into the death.
According to an internal report officers failed to check CCTV footage and did not cross-examine DNA recovered from the scene.
Mr David's family claim he may have been murdered because he was a police informant and have likened the alleged failings in the investigation case to that of Stephen Lawrence, the black teenager who was murdered in Eltham, South London in 1993.
Mr David's mother, Winifred Griffith, told reporters: "If Kester had been a white man the police would have conducted a much more effective investigation."
Two reviews have already been carried out by the force, but with criticism mounting of the Met's race record, Scotland Yard has announced a fresh investigation into the case.
A spokesman for the Metropolitan Police Service said: "Following concerns from Mr David's family, two reviews into the investigation were carried out by senior officers from Enfield borough in September 2011 and January 2012.
"The results of those reviews remain under consideration and detectives from the Homicide and Serious Crime Command are to reinvestigate. They retain an open mind about the circumstances of Mr David's death.
"Officers will be in close contact with the family throughout the investigation to discuss its progress with them."
Ten cases of alleged racism involving 20 officers and a civilian police worker have been referred to the Independent Police Complaints Commission (IPCC) in recent weeks, leading to suggestions that the force has failed to learn the lessons from the Macpherson Report into the Stephen Lawrence murder.