The Police Complaints Authority is currently looking into two cases of former detective Stuart Lewis.

The Police Complaints Authority is investigating Stuart Lewis

One involves the so-called Cardiff Newsagent Three which centres on alleged breaches of the police disciplinary code, and the other involves a complaint made by a Cardiff coroner.

The BBC Wales current affairs series Week In Week Out has spoken to former defendants, solicitors, and a former colleague and has unearthed a pattern of allegations against the detective over many years.

The programme also heard evidence from three men convicted of the murder of Cardiff newsagent Phillip Saunders in 1987.

Former South Wales detective Stuart Lewis is under investigation

Week In Week Out made a programme in 1996 which questioned various aspects of the case, and evidence gathered by Stuart Lewis and others.

After that, their case was referred back to the Criminal Cases Review Commission, who in turn brought in an outside force to investigate.

The report by Thames Valley officers was completed at the end of last year.

The men are now currently on bail awaiting the Court of Appeal hearing in December.

Darren Hall at the time admitted being the lookout and implicated others but has since retracted that statement, blaming police pressure as one of the reasons for his confession.

He said: "The amount of pressure that was put on me by detectives, they would take me upstairs, take me downstairs, they wouldn't let me rest, they wouldn't let me have my solicitor, and it got to the point where I was at breaking point."

Darren Hall said he reached breaking point

A south Wales coroner sent a letter of complaint to the PCA about Stuart Lewis - which the authority said was almost unheard of.

The coroner was unhappy about the handling of an investigation into the death of a Cardiff man, David Kelleher.

The coroner said: "There a number of gaps in the evidence which I feel have not been fully explained.

"I am not convinced, there are so many unexplained questions on how the drug came into his system that I feel that the evidence doesn't fully show how David came by his death. "

He returned an open verdict.

Stuart Lewis, who has since retired from the force, was reluctant to comment on the case.

"The matter is sub judice. It would not be appropriate for me to comment," he said.