FIRST, Caleb Folbigg died at just 20 days old in 1989. Then it was Patrick at eight months in 1991, Sarah at 10 months in 1993 and, finally, Laura at 19 months in 1999.

Their mother, Kathleen Folbigg, is — depending on who you listen to — either Australia’s worst female serial killer, or an innocent woman who doesn’t deserve to be in jail.

According to the police, and a jury that convicted her of the crimes, she is calculating, evil killer who killed her four children by smothering them.

In 2003 she was found guilty of three counts of murder and one of manslaughter and was jailed for 40 years, reduced to 30 on appeal.

Prosecutors said Folbigg was unable to cope with caring for the children. She killed them in a rage and tried to cover it up by blaming natural causes.

But there are others who believe the jury heard flawed evidence, that she is innocent, and that there could be another explanation for the deaths of her children. And they are doing everything they can to have her case reviewed

In June, lawyer Shaun McCarthy from the Newcastle Legal Centre, working with Newcastle barristers Robert Cavanagh, Nicolas Moir and Isabel Reed, sent a petition to NSW Governor David Hurley.

Essentially the petition for judicial review suggests too much weight was placed on Folbigg’s diary entries and the medical evidence relied upon at trial was faulty in regard to what is now known about sudden infant deaths syndrome (SIDS).

It also highlights there was no physical evidence the children had been murdered.

A spokesman for NSW Attorney-General Gabrielle Upton told news.com.au: “I am advised a petition has been made to the Governor and advice is being sought.” He wouldn’t, however, provide a timeline for when a decision could be expected.

At the time the review was being prepared, Monash University professor of forensic pathology Stephen Cordner told the ABC: “If the convictions in this case are to stand, I want to clearly state there is no pathological or medical basis for concluding homicide. It seems not to have been explicitly stated in the trial, but there is no forensic pathology evidence, no signs in or on the bodies to positively suggest that the Folbigg children were smothered or killed by any means.”

THE DIARY ENTRIES

These were crucial in the prosecution case against Folbigg.

In one entry about Laura, she wrote she was “scared she’ll leave me like Sarah”. And then: “I knew I was short tempered and cruel sometimes to her and she left — with a bit of help.”

Writing about one child, she said she just wished she would “shut up” and then after she died said “one day she did”.

In an entry, about the death of Sarah, Folbigg wrote “even though I’m responsible, it’s all right”.

Perhaps most chillingly, she made direct reference to her father, who murdered her mother when Folbigg was a baby herself.

“Obviously, I’m my father’s daughter,” she wrote.

Supporters argue the diary entries simply record a grief-stricken mother and, in that context, the reactions aren’t that unusual.

Another important point was she never attempted to conceal the writing — the question being if they were admissions of guilt in any way, why didn’t she hide them?

THE DISPUTED EVIDENCE

The murder trial was told of how improbable it was that four children from the same family would die of SIDS.

But since then a prominent United Kingdom professor of mathematics, Ray Hill, has questioned whether the jury was ‘‘misled’’ about the probability of multiple deaths in the same family.

In fact, there is precedent for such deaths to occur, as revealed by a major US study, which highlighted two families it had happened to.

That study also found that a family that has lost a child to SIDS was 10 times more likely to become victims again. None of these studies were raised during the Supreme Court trial.

Professor Cordner, writing in a damning 120-page report, considered much of the forensic evidence flawed, which led to murder being the only logical conclusion as to what happened to the children, reported the Newcastle Herald.

‘‘It seems not to have been explicitly stated in the trial, but there is no forensic pathology evidence, no signs in or on the bodies, to positively suggest that the Folbigg children were smothered, or killed by any means,’’ Professor Cordner said in his report.

THE FUTURE FOR KATHLEEN FOLBIGG

With an appeal in 2005 against her convictions having already been dismissed, Folbigg’s only hope rests on whether the judicial review into her case is accepted.

If it isn’t, she will be behind bars for many years to come and will always be branded as the killer of her own four children.