In the case of the death of Anna Jane however, Dr Manock told police that the Brides in the Bath case was relevant in that it suggested a plausible way in which Keogh had murdered his fiaince.

Dr Manock concluded that a "grip pattern" of bruising was consistent with an assailant grabbing Cheney by the lower left leg, lifting it, and in so doing, leveraging Cheney's head under the water of the bath until she was drowned.

Several weeks later, after uncovering evidence that Keogh had faked life insurance policies over Anna Jane and had conducted affairs with other women, police charged Keogh with Anna Jane's murder.

Most South Australians recall a sensational trial involving affairs, money and an elaborate and brutal murder and may be comfortable with the verdict handed down to Keogh.

Keogh however has always protested his innocence, and has been supported by a determined group of criminal law activists as well as his ex-wife and their three daughters, who were not even in their teens when he was convicted.

Fifteen years into a 26 year non-parole sentence, Keogh is imprisoned at Mobilong Prison, Murray Bridge. It is a medium security faciliy reserved for well-behaved prisoners. Before Mobilong, Keogh served in SA’s two maximum security jails, Yatala in Adelaide and then in Port Augusta.

To those who have met him in jail, he appears a well built, thick-necked and with powerful forearms and large hands.

A visitor describes a him as a man with a put-upon air, perhaps wounded pride, perhaps still affected by the events of March 1994 and their aftermath.

Keogh's fourth petition, filed with the Governor in January, contains three small but unmistakable revelations, stemming from the release of previously-confidential documents from the state goverment forensic centre late last year.

The new information in the petition shows that forensic evidence and conclusions that would have undermined the state's case against Keogh were not revealed to the jury.

The petition claims to have identified specific physical evidence in the form of skin samples and a key photograph of the body, as well as written records by one of the state's two pathologists who gave evidence at the trial, Ross James, that undercuts the basis on which the jury deliberated.

Most seriously, the fourth petition alleges the jury was mislead by the two state forensic pathologists Dr Manock and his junior colleague Ross James, in the trial.

In a report written in 2000 by Dr James for his employers the staste Forensic Science Centre and released to the Keogh team late last year, Dr James makes the explosive admittion he did not believe the forensic pathology evidence pointed to Cheney being murdered.

The admition is at odds with conclusions of his former boss, Dr Manock, that Anna Jane was murdered - a conclusion which, while disputed by defence experts, was nonetheless believed by the jury in finding Keogh guilty.

In the report James writes: “I don’t think that the post mortem findings by themselves prove homicide. In this regard, I gather, my views differ from those of Dr Manock. Most importantly I think that the post mortem features are sufficiently suspicious that the case warranted further investigation by the police to clarify the circumstances of her death.”

He goes on to opine about what evidence the jury relied in making its decision, namely the circumstantial evidence about Keogh’s motive, not the pathology: “The evidence that resulted from subsequent police investigations into the circumstances of Miss Cheney’s death provided the Crown with its case. As I understand it, this was the evidence that allowed the jury to reach a verdict and not the pathology evidence.”

Keogh's petition says Dr James did not reveal to the jury his “differing view” to Dr Manock, namely that the pathology evidence was not conclusive of homicide.

The petition says that Dr James mislead the jury, which could not have decided its verdict on the merits.

At the centre of the difference of opinion was Dr Manock's finding that an area of Anna Jane's lower left leg showed a "thumb bruise" - part of the "grip pattern" which included three other bruises on the other side of the leg.

So important to the case was the grip finding that the director of public prosecutions Paul Rofe QC, told the jury in summing up that it was the "one positive indicator" of murder.

However, he added that accepting the grip pattern evidence was not essential to delivering a guilty verdict, pointing to the totality of the circumstantial evidence against Keogh, including his affairs with other women and organising fraudulent life insurance policies over his fiaince.

The fact that Dr James did not believe that the evidence supported a conclusion of murder is hinted-at in the second revelation in Keogh's petition - the key forensic photograph that he denied to the jury ever having seen.

During the second trial the prosecutor produced a black and white autopsy picture of Anna Jane's lower legs.

In a move not made by the prosecutor in Keogh's first trial, which produced a hung jury, Mr Rofe asked Dr Manock to circle the "thumb bruise" on the lower left leg.

Dr Manock circled what he said was the thumb bruise with a red marker, and the print was entered as evidence.

When Dr James was in the stand he volunteered that he had never seen the photograph.

Hand written notes by Dr James, made during his review of Dr Manock's autopsy report and released to Keogh last year, show that Dr James did examine numerous autopsy photographs of Anna Jane's body.

Keogh's legal team is adamant, and has shown The Independent Weekly a photocopy of the notes to support its claim, that Dr James made notes on the photograph which Dr Manock marked for the jury as showing a "thumb bruise".

The notes shown to The Independent Weekly show that Dr James recorded the size and location of all the bruises on the right leg, but failed to record an observation of a “thumb bruise” on the left leg.

In the context of the trial, the effect of Dr James's denial of ever seeing the image was that Dr Manock's evidence, alleging a "grip pattern", was left either unchallenged or unconfirmed.

Also, because Anna Jane's body was released by Dr Manock to be cremated shortly after the autopsy, the photos became the only record of the appearance of the body.

During his testimony at Keogh's trial, Dr James avoided giving a frank assessment of either the grip pattern specifically, or of Dr Manock's homicide conclusion as a whole.

Dr James did not confirm Dr Manock's observation of a "thumb bruise", referring to it only in contingent language:"if it (the bruise) was present as he (Dr Manock) suggests, then a grip mark is the obvious explanation”, he told the jury.

Dr James’ further testimony about the "thumb bruise" was included in comments about observations of microscope slide samples taken from four locations Dr Manock observed bruises on Anna Jane's body. The samples were taken from the inner and outer sides of the lower left leg, the outer side of the right leg, and a small bruise on the top of the head and the shin of the right leg.

In his testimony Dr James referred only to "four histology slides showing bruising" under a microscope. When asked in court if he had seen “four slides of bruising”, Dr James maintained he had.

Keogh's fourth petition takes aim at this assertion and has some additional ammunition due to the emergence, thanks again to the Forensic Science Centre, of a second microscope slide from the alleged "thumb bruise" site.

Under a microscope both slides reveal no sign of bruising.

The fourth petition makes much of the fact that the two negative microscope results were never revealed to the jury, by either Dr Manock or Dr James.

Both doctors referred to them in words to the effect of "slides of bruising", and were never challenged on the individual results by defence lawyer Michael David.

Dr Manock has since been challenged about the slide result, most recently in May, in defending an action by the Medical Board of SA for unprofessional conduct in reaching his conclusions about the Anna Jane death.

Dr Manock has consistently relied on his visual examination of the body, including cutting into the bruises with a scalpel to confirm the presence of blood under the skin, to support his observations of bruising.

In May, under questioning by counsel for the Medical Board, Mark Griffin QC, Dr Manock said that the histology slides were used only to guage the age of the bruises, judged by the presence of white blood cells. Therefore, Dr Manock said, the fact that two of the slides showed no bruising was irrelevant.

At the time of the Keogh trial, Dr James was a specialist in histological, or microscope, examination.

Dr James declined to give evidence at the Medical Tribunal hearing in May.

In previous hearings, including for a Medical Board complaint by Keogh against Dr James for failing to disclose the slide result to the jury, Dr James has provided confusing testimony as to his knowledge of the slide results.

Legal observers say that, even in the most non-controversial of cases, a petition for mercy to the Governor is a long shot.

Keogh’s petition requests the executive arm of government send the case back to the Full Court of the Supreme Court to be reconsidered, based on the totality of information about the case, including any new evidence or admissions, as well as the records of the legal processes that have been followed to date.

However, Keogh's fourth petition, claiming a series of gaps in the evidence presented to the jury, may attract further official scrutiny.

The fourth petition says Dr James's failed to reveal what he knew about the two negative microscope slides; tell the jury that he had seen the key photograph of Anna Jane's lower legs and not observed a "thumb bruise"; believed the forensic evidence did not support homicide and so agreed, with expert witnesses called by the defence. These failures added to the previous material about Dr Manock's conclusions, leading to a conclusion that Keogh did not receive a fair trial.

The petition is careful to present these latest revelations as adding to the other information the Keogh legal team has gathered that, it says, casts doubt on the conviction.

This material, presented in three previous petitions as well as the fourth petition, claims Keogh's trial was unfair because Dr Manock failed to make adequate efforts to rule out alternative causes and manners of death; that his conclusions could not be confirmed because he ommitted to take steps to record his observations and recover an adequate number, and variety, of pathology samples; that the microscope slides refute Dr Manock's "grip pattern" conclusion; and that his reasons for finding that Anna Jane had died from fresh-water drowning, based on red staining of the aorta, is not widely recognised by forensic pathologists.

The main players in Keogh's trial and its long aftermath have moved on, for better or for worse.

Keogh's defence lawyer at trial, Mr David, is now a Supreme Court judge. As is Chris Kourakis, the Solicitor-General who examined Keogh's third petition, over the course of more than three years, before finding the conviction was safe in 2006 in a report that has never been made public or even shown to Keogh’s lawyers.

The chief prosecutor at Keogh's trial, then-DPP Mr Rofe QC was forced to resign by the Rann Government in 2004 due to a high profile botched plea bargain, although he has recently been welcomed back to the fold acting as a prosecutor in a number of current cases including that of cyclist Chris Jongewaard.

Dr Manock is currently awaiting the decision of the Medical Tribunal in a case brought by the Medical Board alleging unprofessional conduct in his autopsy of Anna Jane.

In hearings in May the Medical Board alleged a number of instances of unprofessional conduct, including that Dr Manock failed to investigate other reasonable explanations for Anna Jane's death besides murder by drowning, and that he made incorrect conclusions such as that if Anna Jane had been knocked unconcious, such as in a fall, he would have noticed bruising on the outside of the brain; among other allegations.

Dr Manock made a series of startling admissions under cross examination. Most significantly he conceded that, contrary to his evidence, the fact Anna Jane Cheney had no injury to the brain allowed no conclusions to be drawn about her state of consciousness at the time of death. Dr Manock had put to the jury his view that with no sign of injury she must have been conscious and was therefore deliberately drowned. He now says his evidence was “erroneous”.

Even so Dr Manock denies the charge and, under questioning from the Medical Board's lawyer Mark Griffin defended his conclusions, on the whole, as reasonable.

Dr James too has been the subject of a complaint of unprofessional conduct by Keogh before the Medical Board. The Board last year censured Dr James for alleged ommissions in his evidence at the Keogh trial.

This year however, the full court of the Supreme Court confirmed an earlier single-justice decision clearing Dr James of the complaint, saying that Dr James's evidence was, broadly speaking, acceptible for an expert witness.

Keogh has applied for leave to appeal this decision to the High Court.

Keogh is also preparing an action in the Supreme Court, asking for his conviction to be set-asside.

The new action is expected to claim that the verdict in the Keogh trial was arrived at by fraud.