Relatives of private detective Daniel Morgan have said they are "devastated" after his multimillion-pound murder case collapsed on the 24th anniversary of his death.
The family called for a judicial inquiry into the course of events and declared: "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 on Friday 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.
Rees, 56, Garry Vian, 50, and his brother Glenn, 52, were discharged from court. They all denied murder. Associate James Cook was freed in November last year and former detective sergeant Sid Fillery, 63, was discharged in February last year.
Mr Morgan's brother Alastair, 62, 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.
The family called on Home Secretary Theresa May to order a full judicial inquiry into the handling of the case by the Metropolitan Police and the Crown Prosecution Service.
A senior Scotland Yard detective on Friday apologised to Daniel Morgan's family as he admitted "police corruption was a debilitating factor" in the collapse of the murder case.
Detective Chief Superintendent Hamish Campbell said the outcome of the long-running investigation was "wholly regrettable". 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."