Friends and supporters of Nicky Jacobs, who was cleared of murdering PC Keith Blakelock, said the Crown Prosecution Service and Director of Public Prosecutions had questions to answer on why such a "farcical" case came to trial.
Stafford Scott, the co-ordinator of the Tottenham Rights group and one of Mr Jacobs' most vocal supporters, told reporters outside the Old Bailey, "It is not a day of joy. Everybody should be able to take the notion of receiving justice as standard."
Referring to the Blakelock family, Mr Scott added: "This must have been terrible for the family. They have been conned by the Metropolitan Police Service who said this would bring justice."
Winston Silcott, who was found guilty at the Old Bailey of murdering PC Blakelock in 1987 before his conviction was quashed in 1991, claimed the police had brought the case because they were "bitter about what happened".
The Crown Prosecution Service (CPS) has insisted "it was right" to bring a case against Nicky Jacobs over the murder of PC Keith Blakelock.
Jenny Hopkins, deputy chief crown prosecutor for CPS London, said: "This case was charged under the Full Code Test of the Code for Crown Prosecutors following a review of the material from all three police investigations spanning over 20 years.
"Following this review we concluded that there was sufficient evidence for a realistic prospect of conviction and it was in the public interest to charge Nicholas Jacobs with the murder of PC Keith Blakelock.
"It was right that all the evidence in this case was put before a jury and we respect their decision."
Sir Bernard Hogan-Howe paid tribute to the wife of Keith Blakelock today as he said efforts to find those responsible for the policeman's murder will not stop.
Jacobs, 45, was cleared of the murder of Pc Blakelock who died at Broadwater Farm in 1985 after suffering multiple stab wounds.
"The patience and determination that Keith's widow, Elizabeth, has shown over the years as she has pushed for answers about her husband's murder has been inspirational. She so richly deserves those answers and justice," the Metropolitan Police Commissioner said.
"We accept the decision of the jury and our work to bring those responsible for Keith's murder to justice will not stop. I would like to thank the investigation team for their dedication and hard work over a number of years."
The family of Pc Keith Blakelock said they were "extremely sad and disappointed at the verdict" following the acquittal of Nicky Jacobs.
A jury took just six hours to clear the 45-year-old of the murder of Mr Blakelock who was stabbed over 40 times in an attack at Broadwater Farm in 1985.
"We are obviously extremely sad and disappointed at the verdict. We viewed this trial as an opportunity to see some form of justice served for Keith," a statement on behalf of the family said.
"There were many people involved in a murder on that night of 6 October 1985 and it is regretful that no-one has yet to be found guilty despite the number of people with knowledge of the events of that night."
The family, who thanked everyone involved in ensuring the case was brought before a jury, said they hoped more people would come forward to bring those responsible to justice.
Nicky Jacobs punched the air after a jury cleared him of the murder of Pc Keith Blakelock.
He subsequently sat down and sobbed before being taken from the dock.
The 45-year-old's supporters in the public gallery including Winston Silcott - whose conviction for the murder of Pc Blakelock was quashed in 1991 - shouted "Yeah, yeah" and called out "Brother, brother" as the verdict was announced.
Courtenay Griffiths QC, for the defence, said: "I'm delighted, I think the jury reached exactly the right verdicts. Now I have to go and see my client."
Police have said they will not give up on finding those responsible for the death of Pc Keith Blakelock following the acquittal of Nicky Jacobs.
Describing his murder in 1985 as "barbaric", Assistant Metropolitan Police Commissioner Mark Rowley said:
Sadly, Keith's widow, family and friends still have not seen anyone brought to justice for his murder.
The dignity, extraordinary patience and courage they have shown in their nearly thirty year quest for justice is humbling.
We will not give up on bringing Keith's killers to justice. There are people who know exactly who took part in the attack on Keith and people who took part themselves. It is not too late for you to come forward.