Carl Bridgewater: Shot in the head

The men were accused of fabricating evidence and committing perjury but the CPS said there was "insufficient evidence for a realistic prospect of conviction for this allegation".

The case was referred to the CPS after the men convicted of killing schoolboy Carl Bridgewater in 1979 had their convictions quashed. James Robinson, Michael and Vincent Hickey were freed last July.

Patrick Molloy died in prison in 1981. They became known as the Bridgewater Four and had spent 18 years in jail.

The 13-year-old boy was shot in the head at close range in September 1978 after he stumbled across a burglary at Yew Tree Farm near Stourbridge, in the West Midlands.

'Not enough evidence'

The new Director of Public Prosecutions, David Calvert-Smith, said he appreciated that the decision not to take action against any officers could be seen as "difficult to understand" following the men's release.

But he said the job of the Court of Appeal, which had access to material that would not be admissible in a criminal trial, was to decide whether a conviction was safe.

The CPS could only take action if there were enough evidence that could be put before a court of law.

The three men's solicitor, Jim Nichol, told the BBC he is considering applying for a judicial review to challenge the CPS decision.

'Forged' confessions

Eight detectives - one of whom has since died - were implicated in the Court of Appeal ruling over the way Staffordshire Police gathered evidence in the case.

Allegations focused on claims that Pat Molloy only confessed to being at the scene of the crime after he was shown records of a forged interview with co-defendant Vincent Hickey.

Officers also allegedly falsified evidence relating to a conversation during a car journey with Mr Molloy.

But the CPS said Mr Molloy's death meant it would be very difficult to back up the claims. Neither the accuracy of the confession statement nor the car conversation were challenged by his defence at his trial or on appeal, and Mr Molloy had been given the opportunity to retract his confession.

Officers also allegedly fabricated confessions made by Michael Hickey.

Michael Hickey: Suffered mental health problems since release

The CPS said while the Court of Appeal had decided this was probably the case, much stronger evidence would be needed to bring a criminal prosecution.

Such a prosecution would also be made difficult by the current state of Mr Hickey's mental health, which meant he would not be able to give evidence in a trial, as well as conflicting evidence he had given at his original trial.

The CPS said Merseyside Police had investigated the allegations and it had taken expert legal advice before arriving at the decision not to prosecute.

Decision 'outrageous'

Michael Hickey's mother, Ann Whelan, expressed her fury at the news that the officers will not be tried.

"This decision is absolutely, horrendous, outrageous, and deplorable. These men served almost 100 years between them, and I will not rest until the police officers who wrongly put them behind bars are themselves," she said.

"The evidence was manufactured and perjured. These officers lied, they are the criminals in this case."

She added that Michael Hickey's mental state would only improve once those who put him in prison were punished.