British police have passed to prosecutors secret files on the death of New Zealand teacher Blair Peach - killed during an anti-racism march in London 30 years ago.
The prosecutors will determine whether any further investigation is necessary into the death of Peach, 33, after a blow to his head at a demonstration against the National Front in Southall, West London.
His skull was crushed.
Witnesses say at the time they saw police officers attack Peach.
A pathologist's report said the injury to his skull was likely to have been caused by a lead weighted rubber cosh, or hosepipe filled with lead shot.
Police have now asked the Crown Prosecution Service to conduct an independent review of internal reports that examined if there was evidence that he was killed by police, The Times newspaper reported on Tuesday.
Sources close to the process said murder or manslaughter charges were unlikely, but individuals could face charges of perverting the course of justice.
Police solicitors recommended that the report be given to prosecutors for a final appraisal, which is likely to delay its release until at least February.
A Metropolitan Police spokesman told the newspaper the report was formally handed to the CPS today.
"At the request of the Met the CPS has agreed to review the Blair Peach Report and provide advice as to whether any further investigation into any aspect of the matter would be justified.
"This independent oversight should provide clarity to the family of Blair Peach and the public that the Met has exhausted all investigative options in relation to this historic case".
In June, Commissioner Sir Paul Stephenson said the report from the original investigation should be published, possibly by the end of the year, with some details censored.
The death of Peach on April 23, 1979 came when Metropolitan police officers were accused of lashing out at protesters opposed to attempts by the National Front to hold a meeting at the heart of the largely Sikh community in Southall, west London.
Commander John Cass, who originally investigated the case in 1979 as the head of the Metropolitan police force's complaints bureau, was believed to have identified several officers as possible suspects in the killing and accused others of thwarting his inquiries.
Suspicion fell on the Special Patrol Group (SPG), an elite group of officers trained to deal with riots.
When Cass raided SPG headquarters, he uncovered a stash of weapons including a metal cosh - but not the weapon that killed Peach.
In July, Alan Murray, a former Scotland Yard inspector, said he believed that Peach was murdered, but not by police.
Murray, now a 59-year-old Sheffield University lecturer, led a unit of the SPG, but denied killing Peach and said he did not believe anyone in his unit was responsible.
Scotland Yard has previously secretly reopened an inquiry into the death: a second Met commander in charge of the force's complaints bureau, Ian Quinn, re-opened the file about 10 years ago for a "review", and produced a separate report on the death.
The existence of Mr Quinn's report - revealed earlier this year - shocked some family and friends of Peach, including a brother, Philip, who said: "I would certainly have expected to have been told that there was a review of the case...the Met have kept this completely secret."
