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Australia's 'worst female serial killer' Kathleen Folbigg released after help from Spanish scientist

The Spanish scientist Carola García de Vinuesa
The Spanish scientist Carola García de Vinuesa Copyright Australian National University
Copyright Australian National University
By Laura Llach
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Kathleen Folbigg spent twenty years in prison being demonised for killing her four children, until a Spanish scientist helped to free her, and expose one of Australia's biggest injustices.


An Australian woman who spent 20 years in prison for killing her four children was pardoned and released on Monday following an inquest into her guilt.

Kathleen Folbigg, now 55, was dubbed "Australia's worst serial killer" after being convicted in 2003 of murdering three of her children, and convicted of manslaughter in the death of the fourth. 

According to prosecutors, her children, aged between nine weeks and three years, had been suffocated to death by Folbigg, who has always rejected these accusations, claiming that each of their deaths was linked to a natural cause.

A pardon on the grounds of reasonable doubt was seen as the quickest way to secure her release from prison -- a subsequent inquiry could see her convictions quashed completely. 

Kathleen Folbigg spent her two decades in prison being demonised. 

Once the most reviled name in Australia, Folbigg has been cleared thanks in part to a Spanish scientist Carola García Vinuesa, who, along with other colleagues, has managed to show the children could have died of natural causes.

"The theory that she had killed her children had no evidence. The only evidence was circumstantial, because she was the one finding them dead," Vinuesa told Euronews.

"Folbigg is very grateful, not only to us - the scientists - but also to her lawyers, who have done most of the work for free," she adds.

Joel Carrett/AAP
FILE - Kathleen Folbigg appears via video link during a convictions inquiry at the NSW Coroners Court, Sydney, Wednesday, May 1, 2019.Joel Carrett/AAP

Australia's 'most notorious killer'

The first to die was her son Caleb, aged 19 days. One night, Kathleen woke up because she needed to go to the toilet. She checked on her baby and realised he wasn't breathing.

"There's something wrong with my baby," she shrieked. Her husband came running, and they tried to resuscitate the child, but by the time the ambulance arrived he was dead.

After this she lost Patrick when the baby was just eight months old. Ten-month-old Sarah and 18-month-old Laura died later. Two of the children had died of sudden infant death syndrome. The trauma was huge so Folbigg and her husband’s relationship deteriorated and the couple decided to get a divorce.

Years later, her former husband found Folbigg's personal diary. Some of the lines his ex-wife had written set alarm bells ringing, like when she wrote that her daughter Sarah had "gone away with a little help". He was so shocked he gave the diaries to the police.

Although there was no evidence against her, at the time, there was a lot of weight put placed on the 'Meadow's Law' theory about sudden infant deaths, which has now been discredited.

British pediatrician Roy Meadow believed that one sudden death is a tragedy, two are suspicious and three is considered murder until proven otherwise. His theories have since been largely debunked, and he was struck off the UK medical register for a number of years. 

How did a Spanish scientist get involved in the case?

In Australia, the jury convicted Folbigg accusing her of suffocating her four children, but she always maintained her innocence. 

Nobody believed her story, until Vinuesa decided to help her.

The Spanish scientist had never heard of Folbigg's case, until one afternoon when she received a call from a former student. 

David Wallace, who did his dissertation with Vinuesa's research group, was watching a television programme when Folbigg popped up on screen.


Wallace, who had also studied law, had his doubts and wanted the scientist's opinion. 

"He called more researchers, but the rest must not have been interested. I was really surprised when I heard about the case," says the Spaniard, whose team had pioneered the sequencing of the human genome.

"Two of Folbigg's children had been very ill before dying and this really made me question the case, so I contacted Folbigg's lawyers to tell them it was worth doing genetic research," she adds.

Genetic research

The researcher knew that up to 35% of cases of sudden death can be explained by genetic factors, and with this in mind, Vinuesa called her colleague, geneticist Todor Arsov. 

They decided to draw up a list of genes that can cause sudden death.


The next step in their scientific investigation was to visit Folbigg in prison and sequence her genome. 

"We discovered that there was a mutation in a gene that encodes calmodulin, and this is one of the most well-known causes of sudden death in infancy," Vinuesa tells Euronews.

"I wrote to Kathleen's lawyers and told them we had found this mutation. We wanted to do a full cardiovascular work-up. We also needed to sequence the childrens' and father’s genome," she adds.

In 2018, a petition raising doubts over some of the evidence presented at Folbigg’s trial led to the first of two inquiries into Folbigg’s case. Two teams of immunologist-geneticists were called.

Vinuesa's team found a gene mutation in two of Folbigg's daughters, while the other two children had severe epilepsy and respiratory distress.


They contacted Peter Schwartz, one of the most famous geneticists in the world, working at the Auxological Institute in Milan. He had just studied a similar case and, after analysing the information, agreed that it was the most likely cause of the children's deaths.

According to Australian press, the judge decided that he preferred the evidence of the diaries and stated he didn't need a psychiatrist to explain the mother’s diary entries.

He also sided with arguments presented by the prosecution's team of immunologists.

At the original trial, the jury never had access to Folbigg's full diaries, only excerpts taken out of context in the aftermath of the deaths of her children. 

"Those notes were not a confession, she only said she felt guilty. In this last inquiry into Folbigg’s case, nine experts - forensic experts, psychiatrists, linguists - analysed it and agreed that they were expressions of a grieving mother and did not contain an admission of criminal guilt," says Vinuesa. 


Fighting for Folbigg's release

When talking about the personal toll, Vinuesa says she had to face the frustration felt when the court did not understand science.

Despite the initial verdict, Vinuesa and her colleagues published their findings and asked the Australian Academy of Science to support the science. "Since all legal pathways had been exhausted, they made a petition to the governor of New South Wales. They asked for her pardon”.

This petition was signed by 90 scientists and medical experts from around the world, among them were two Nobel laureates.

Folbigg’s freedom wasn’t an option at first, but this letter changed the social climate and improved her life in prison. "Her colleagues, who mistreated her because she was a child murderer, changed their attitude and helped her," she says.

In May 2022, the governor had his decision made: there would not be a pardon for Folbigg, but he announced a new review of the case.


This time round they had more support. "The Australian Academy of Science got legal representation and had a team of lawyers who were able to advise who were the best experts in the world in each field. Also what kind of questions they should be asking these experts."

"It's making sure that the system is fair and can be assessed transparently."

After Folbigg’s legal pardon, Vinuesa feels satisfied at last, but looks back with a bittersweet feeling. 

"Scientifically it has been a challenge. It has been a very hard, intense and sometimes a painful process".

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