Blair Peach, 33, died after was hit over the head by an officer at an anti National Front demonstration in Southall, west London, in 1979.
The officers involved made "false statements" regarding details surrounding his death, a previously secret report found.
Met police chief Sir Paul Stephenson said the report made "uncomfortable reading" but despite this the force insisted that nobody involved would face prosecution.
Mr Peach's partner Celia Stubbs said the findings "vindicated" her belief that the activist was killed by police.
The document - written by Commander John Cass, a former senior officer at the Met's internal complaints department, singled out the actions of the three officers, named as E, H and F.
He wrote: "The most serious aspect of this case has, without doubt, been the obstruction of the investigating officer in execution of their duty."
Commander Cass recommended the three officers should face prosecution.
He added: "I strongly recommend that proceedings be taken against Officer E, Officer H and Officer F for obstructing police in the execution of their duty, conspiring to do so, and attempting or conspiracy to pervert the course of justice."
Mr Peach was struck on the head during the protest on April 23 1979. He died in hospital of head injuries the next day.
Some 14 witnesses reported seeing him being hit by a police officer.
The names of the officers and witnesses involved were removed from the report for legal reasons.
Police insisted this had not been done to prevent embarrassment to the force.
The report said it could "reasonably be concluded that a police officer struck the fatal blow".
It continued: "The attitude and untruthfulness of some of the officers involved is a contributory factor.
"It is understandable that because of the events of the day officers were confused, or made mistakes, but one would expect better recall of events by trained police officers.
"However, there are cases where the evidence shows that certain officers have clearly not told the truth."
Mr Peach's partner Celia Stubbs said she was delighted to finally see the report.
She said: "I never really believed we would get it.
"It is fantastic after 31 years. I have only read 200 pages of the report but I feel that we have really been vindicated because we have always said that Blair had been killed by a policeman.
"It says in the report that it was an officer that struck Blair.
"I never really expected a prosecution. I don't regret that, I am just pleased that we have the report so we can see what happened on the day."
Her solicitor Raju Bhatt added: "What Celia and the family expect and deserve is a clear unequivocal acknowledgement from the Commissioner that the evidence establishes that one of the officers of the Metropolitan Police was responsible for Blair Peach's death."
The decision to publish came after public pressure to reveal the almost forgotten review in the months after the death of Ian Tomlinson during G20 protests.
Sir Paul said: "I have to say it's a matter of deep regret, and I have to say really, that I'm sorry that over 31 years since Blair Peach's death we've been unable to provide his family and friends with a definitive answer regarding the terrible circumstances that he met his death.
"I've personally written to Blair Peach's brothers and his partner to express this to them.
"It might be 31 years ago but I also have to say that the material published today makes for some uncomfortable reading.
"Uncomfortable as I've said, because there is no definitive final answer to his family and friends, uncomfortable that no officer came forward to declare use of force in relation to Blair Peach.
"Uncomfortable with Commander Cass's conclusions that officers had not been truthful with his investigative team."
The Met later released a statement confirming that nobody would face prosecution for Mr Peach's death.
A spokesman said: "We have gone to great lengths to ensure that all investigative options currently available have been exhausted.
"To this extent the Crown Prosecution Service (CPS) has provided us with independent advice stating that there is nothing which would currently justify carrying out a further investigation."
The Met later explained the legal reasons behind the removal of officers' names from the report.
A spokeswoman said: "Some of the information has been redacted to prevent the identification of members of the public and police officers who contributed to the investigations into Blair Peach's death.
"It is only information by which an individual could readily be identified, such as names, contact details and, in the case of police officers, serial numbers that has been removed.
"This has been done in order to comply with the Data Protection Act 1998, the Freedom of Information Act 2000, the Human Rights Act 1998 and the individual's rights at common law.
"All redactions were done by independent legal counsel and go no further than is necessary for compliance with the legal duties mentioned above."
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