The murder of policeman Keith Blakelock during a fierce inner city riot was one the most brutal and controversial crimes of the last twenty years. The 40-year-old constable was hacked to death with a machete in October 1985 during disturbances on on the Broadwater Farm estate in Tottenham, north London. Winston Silcott, along with two other men, was wrongly convicted two years later of murdering the father-of-three. In 1991 Mr Silcott, Mark Braithwaite and Engin Raghip had their convictions overturned because of ''unsafe'' police evidence. Last autumn it emerged that the Metropolitan Police were reinvestigating Pc Blakelock's death. The new probe was launched after a three-year review of the Blakelock case identified ''new lines of inquiry'' which could provide a breakthrough. The investigation was also to look into the attempted murder of Pc Richard Coombes during the riot who was injured with a machete and never returned to active duty. Earlier this year, in his first televised interview, Mr Silcott called for a public inquiry into the case. During the programme Mr Silcott, who did not give evidence during his trial, said he had fallen asleep in a friend's house on the night of the killing, rather than taking part in a march on Tottenham police station. He said his first knowledge that a police officer had died came when there was cheering in the house where he was. At the time of Pc Blakelock's murder, Mr Silcott, 44, was on bail for the murder of boxer Anthony Smith, 24, whom he was accused of stabbing to death in a fight in December 1984. He was later convicted of the murder and was already in prison during the time of his trial for the murder of Pc Blakelock. In the BBC documentary Mr Silcott said he did not give evidence during the Pc Blakelock murder trial because he feared the jury would be prejudiced against him if details of his existing murder conviction were released. He said: ''I think there should be a public inquiry from start to finish and look into every aspect throughout the whole thing.'' Mr Silcott was released from prison last October after serving 17 years for murdering Mr Smith. He accepted £50,000 compensation from the Metropolitan Police after his conviction for Pc Blakelock's murder was overturned. Two officers involved in the original Broadwater Farm inquiry - former Detective Chief Superintendent Graham Melvin and ex-Detective Inspector Maxwell Dingle - were charged with fabricating evidence but were cleared at the Old Bailey in 1994. The 1985 riots were sparked by the death of 49-year-old Cynthia Jarrett during a police raid. She collapsed and died of heart failure after four policemen burst into her home and 250 police officers were injured during the subsequent uproar at the Broadwater Farm estate.