Mark Grommek lived above the flat in which Lynette White was stabbed to death
A key witness in a murder trial nearly 20 years ago has admitted perjury at Cardiff Crown Court.
Mark Grommek changed his plea to guilty after a judge said his treatment by police investigating the 1988 murder of prostitute Lynette White did not amount to a defence of duress.
Two other witnesses also admitted perjury, it has now been revealed.
The jury heard false evidence led to murder charges against five men. The real killer was jailed in 2003.
Angela Psaila and Leanne Vilday's pleas of guilty to perjury could not be recorded while Grommek was still on trial.
He was accused of giving false evidence against two of five men charged with stabbing Ms White in Cardiff in 1988.
Mr Grommek, 50, lived above a flat in Butetown in which Ms White was stabbed to death in the docks area of Cardiff in February of that year.
The jury was told by the prosecution how Grommek's false evidence led to five men - Stephen Miller, Yusef Abdullahi, Anthony Paris, John Actie and Ronnie Actie - being charged with murder.
It became one of Britain's most notorious miscarriages of justice.
The real killer, Jeffrey Gafoor, a client of Ms White, eventually admitted murder in 2003 and was sentenced to life imprisonment.
During the trial the jury was played tapes of police interviews with Mr Miller to give them "a flavour" of the behaviour of officers as Grommek described it.
Initially denying three charges of perjury, claiming he lied under duress, Grommek changed his plea on Monday.
Lynette White was stabbed more than 50 times in a Cardiff flat
In his opening statement, Prosecutor Nicholas Dean QC Dean told the court Grommek initially said he knew nothing of the circumstances of Ms White's death.
However, in late 1988, he changed his story, saying he had seen four men outside the James Street flat.
Mr Dean said: "Mr Grommek now says that in November and December 1988, the police used a combination of suggestion, persuasion and verbal bullying to get him to agree to a version of events that was to implicate in particular Ronnie Actie and Yusef Abdullahi.
"The prosecution in this case fully accepts that Mr Grommek was indeed persuaded to accept a version of events, that he was cajoled into signing statements he knew to be an absolute tissue of lies."
In telling lies however, Grommek acted "selfishly and his own self-interest", Mr Dean said.
His treatment by police is "not a defence to the charges of perjury," he said.
Gafoor's conviction sparked an inquiry into the way the original murder investigation was conducted.
When police interviewed Grommek about that in October 2004, he said he lied because he wanted everything "over and done with".
Grommek's barrister, David Aubrey QC, said: "The defendant has instructed us to inform the court that he is prepared to make witness statements and give evidence in court in due course, if he is required, against any police officers who may be charged."
Explaining his decision not to allow the defence of duress, Mr Justice Maddison told the jury that Gtrommek had made a "large number" of witness statements in 1988 and had accepted his evidence at magistrates court and at two crown court trials was untrue.
"To put it in a nutshell, he said it all came about because he had been mistreated and abused by the police in various ways," said the judge
He said that while the prosecution accepted he was mistreated by the police in 1988, the charges arose from statements he gave "a significant time later".
He said Grommek was not threatened with violence after November 1988, but the charges related to evidence he gave months later.
The judge told the jury he could, however, take into account Grommek's treatment by police in sentencing him.
Grommek was released on unconditional bail for the preparation of pre-sentence reports.