Nobody will be held to account for the collapse of Britain’s biggest police corruption trial despite a string of mistakes by inexperienced prosecutors and police mishandling of vital documents, according to two official reports.

Eight police officers accused of fitting up the so-called “Cardiff Three” for the murder of prostitute Lynette White in 1988 walked free in 2011 after a court was told that some documents linked to the case had been shredded. A month later they were found in the office of the senior investigating officer as he cleared out his desk after being forced into retirement, the inquiries found.

The reports concluded that police and prosecutors had not made wrong decisions for “improper reasons” before the collapse of the case that cost an estimated £30 million, and therefore would not face misconduct hearings. The conclusion sparked renewed demands from the men wrongly prosecuted for the killing to demand a public inquiry, saying the case raised serious doubts about the criminal justice system’s ability to investigate itself.

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Three men – known as the Cardiff Three – were wrongly jailed for life in 1990 for the murder of Miss White, who was stabbed more than 50 times in her Cardiff flat. Two others were acquitted. One of those jailed men, Stephen Miller, was subjected to days of hostile questioning from police until he “confessed” after more than 300 denials.

The men were released in 1992 on appeal before advances in DNA led to the conviction of the real killer, Jeffrey Gafoor, in 2003. The conviction of Mr Gafoor set the process in motion for detectives working on the original inquiry to stand trial but a string of mistakes meant that the first case collapsed in 2011 with a second, that would have seen four more officers stand trial, also abandoned.

One of the Cardiff Three, Tony Paris, said: “I was robbed of the chance to see justice done to the police officers who stood accused of fitting me up for murder. Only a public inquiry stands the chance of getting to the truth and of bringing those that have failed me to account.”

The case against the officers from South Wales police collapsed after a series of problems over disclosure, the process of handing over prosecution documents to defence teams to allow them to prepare for the case properly and ensure a fair trial.

Responsibility fell to a young barrister – known as “baby counsel” in the business – to handle a million pages of evidence and documents with poor levels of supervision, according to a report by inspectors of the Crown Prosecution Service. The final straw was the loss of copies of four documents that criticised how police conducting the inquiry. A report by the police watchdog concluded that the now retired officer, Chris Coutts, had not ordered their destruction.

The acquittals meant the South Wales officers would not stand trial again, even though key witnesses had been assured that they had manufactured evidence and could face a minimum of ten years in prison if convicted, according to notes of meetings detailed in the inspectorate report.

Lawyers for the three survivors of the original five prosecuted said the reports left many questions unanswered and demanded Home Secretary Theresa May order a public inquiry into the 25-year saga. Mrs May has previously resisted the demand.

Kate Maynard, the solicitor for two of the men, said: “The investigations indicate a disturbing degree of complacency and incompetence on the handling of disclosure by the prosecution team. This is hard to understand in a trial of such importance and expense, following an investigation that had dragged on for years.”

A Crown Prosecution Service spokesman said the report made clear that “no one individual was to blame” and said that it had changed its practices.

“They did not rise to the unprecedented challenges of this prosecution, but they did not wilfully neglect their duties or engage in anything that could be described as gross misconduct,” he said of prosecutors.

South Wales police said: “It is clear from the reports that there was no misconduct on the part of officers and prosecutors, who acting in good faith made errors which reflected the wider challenges the prosecution team had faced from the outset.”