The family of private detective Daniel Morgan was devastated today after his multi-million pound murder case collapsed on the 24th anniversary of his death.
They called for a judicial inquiry into the blow saying: "The criminal justice system is not fit for purpose."
Mr Morgan was found with an axe in his head in a pub car park on March 10, 1987, in a case which has become one of Britain's longest unsolved murders.
No-one has been brought to justice despite five police inquiries and three years of legal hearings, unofficially estimated to have cost around £30 million.
Five people were arrested in 2008 but two, including a former detective accused of perverting justice, were discharged after a string of supergrasses were discredited.
The final blow came today when the Crown Prosecution Service dropped the case against the remaining three - Mr Morgan's former business partner Jonathan Rees and brothers Garry and Glenn Vian.
Mr Morgan's mother Isobel Hulsmann, 83, who had travelled from her home in Hay-on-Wye, Powys, to lay flowers at her son's grave in London, was being comforted by her family today.
They had been praying for justice after so many years and were left frustrated and confused after being warned of today's outcome.
Mr Morgan's brother Alistair, 62, said: "My family is devastated by this news.
"We put some flowers on the grave. It's just horrible."
Mr Morgan said he believes there have been a number of police cover-ups over the years and alleges that his brother was murdered because he was about to expose police corruption.
He added: "It was obvious my brother was going to blow the lid off the links between the police and criminals."
The family was behind the current investigation by hand-picked Scotland Yard officers.
But the failure of the case, which collapsed before a jury was even sworn, throws up serious questions about the use of supergrass deals offering reductions in sentences in return for evidence, and the offer of rewards.
Underworld figures and their associates had volunteered to give evidence after a £50,000 reward was offered.
One had a lengthy prison term reduced after agreeing to be a prosecution witness.
And a woman, a former partner of James Cook, who was charged with murder but freed last year, was discredited after claiming that up to 30 murders had been committed. Extensive searches produced no bodies.
Scotland Yard was even accused of buying a house next to one of the defendants in order to plant listening bugs in the walls.
The halting of the case is a major embarrassment for Scotland Yard and the file will remain open until the killer is caught.
Rees, 56, Garry Vian, 50, and his brother Glenn, 52, were discharged from court today. They all denied murder.
Associate Cook was freed in November last year and former detective sergeant Sid Fillery, 63, was discharged in February last year.
Lawyers for Rees and the Vian brothers had brought about a three month hearing to review the police handling of 18 crates of material relating to potential witnesses.
It followed accusations that police had conspired not to reveal files in an attempt to prevent the defendants getting bail as the on-off legal hearings dragged on.
Just as written submissions were handed to the judge Mr Justice Maddison last Friday, the prosecution broke the news that four other crates of material had been unearthed.
Also, the two prosecution counsel might have to give evidence about disclosure and therefore be forced to hand over the enormous back-workload to other prosecutors.
Prosecutor Nicholas Hilliard QC had told the judge on Monday: "It's on the cards."
The blow comes after a fifth police inquiry and an inquest into the killing outside the Golden Lion pub in Sydenham, south London.
Previous attempts at prosecutions have also ended in failure due to lack of evidence against various defendants.
Mr Morgan, 37, a father-of-two, had been a partner in Southern Investigations, in Thornton Heath, south London.
The latest inquiry was started in 2005 after pressure from Mr Morgan's family through the "Justice For Daniel" website.
Police vowed to leave no stone unturned but were hampered by a vast paper-trail involving other investigations.
The judge said it was a case where "nothing is straightforward".
Defence counsel complained that the prosecution had not disclosed all the material the police had stored.
Some 750,000 pages were sifted through as several more boxes were uncovered.
The judge threw out the evidence of a supergrass who had earlier signed a supergrass deal and seen his sentence reduced from 28 years to three years.
He was the only potential witness to claim he had seen the defendants in the Golden Lion.
Detectives were criticised by the defence for their handling of the crook and the lengths they went to to present him as a credible witness.
Mr Justice Maddison decided he was not a witness who could be relied on.
The defendants were in custody until March last year when they were given bail after the judge found the prosecution had not shown "due diligence" in preparing the case.
By the end of the pre-trial hearings they were no longer bothering to sit in the dock but watched proceedings from the back of the court.
The frustration of Mr Morgan's family as police officers were quizzed by defence lawyers erupted at a previous hearing when Mr Morgan's sister Jane rose to her feet and challenged a barrister with the words: "You really are an obnoxious little man."
It was the second time Rees had been charged with the murder but the previous prosecution was also aborted.
The defence argued that a motive had not been established and there were a number of people who may have wanted to see him dead.
They said there was no credible evidence against the defendants and no DNA linking them to the crime.
Mr Hilliard offered no evidence on behalf of the prosecution.
The three defendants stood at the side of the dock as Mr Justice Maddison told them they were free to go as he had entered not guilty verdicts.
Outside court, Rees said he was angry at the way they had been treated and continued to protest his innocence.
But the judge told the court that, whatever the outcome of any trial would have been, the Metropolitan Police had been right to make the arrests.
He said: "There is no doubt, it seems to me, that given the evidence available to the police before these proceedings were instituted, the police did have ample grounds to justify the arrests and prosecution of the defendants."
He said that following the loss of witnesses and the mountains of paper involved, the prosecution decision had been "principled and right".
He added: "This is the end of a long and exhausting road."
Mr Justice Maddison paid tribute to the family of Mr Morgan, who had been the victims of a "dreadful murder".
He said he could understand if they had been confused at times about what was going on but the case had been full of complex issues.
Mr Hilliard had earlier made an apology to the family in court.
"I apologise to them that we have reached the position we have," he said.
Mr Hilliard said the case had involved an unprecedented amount of paperwork and police officers had to sort through material covering more than 20 years to see what they thought was relevant.
He said the disclosure process had been so complex that the prosecution could not be sure that the defence would have all the material it should have.
And it was also not possible to say that the prosecution would result in a conviction.
Richard Christie QC, for Rees, told the court that the decision was overdue following the making of six different trial dates.
Outside court, Detective Chief Superintendent Hamish Campbell also apologised to the Morgan family.
He said: "This was a difficult decision to have reached and we recognise the severe disappointment this will cause and how deeply upsetting it is to Daniel's family and friends.
"Within this formidable and complex murder inquiry it is deeply regrettable that it has not proved possible to guarantee to the court that all the relevant material has been presented to ensure a fair trial.
"On behalf of the Metropolitan Police Service, I sincerely apologise to Daniel Morgan's family and it is with considerable regret that a trial cannot proceed."
He added: "This current investigation has identified, ever more clearly, how the initial inquiry failed the family and wider public.
"It is quite apparent that police corruption was a debilitating factor in that investigation. This was wholly unacceptable."
Jonathan Rees said outside court: "I should never have been prosecuted."
A statement then read on his behalf said: "I have protested my innocence throughout.
"I have chased the police on many occasions to follow leads, which they have not.
"When Daniel Morgan was killed it was an awful shock to me and to our business. I lost a friend and a business partner.
"My sympathy goes out to Danny Morgan's family, who have been fired up by police over the years to believe an untrue version of events.
"The truth is that there were up to 40 alternative suspects that police did not properly investigate."
He criticised detectives who, he said, had taken people with mental health problems and career criminals seriously.