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Australian Mother Convicted Of Babies' Deaths Freed From Prison After Gene Discovery

Once branded "Australia's worst female serial killer,” Kathleen Folbigg has now been pardoned after two decades in prison.


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Blurred waving flag of Australia behind barbed wire prison fence.

Experts have commented on how this case will have a massive impact on the way science helps to guide criminal cases.

Image credit: Novikov Aleksey/

After two decades in prison, Kathleen Folbigg has been pardoned and released thanks to new genetic evidence that suggests she did not kill her four children.

Tabloid newspapers branded Folbigg as "Australia's worst female serial killer.” In October 2003, she was sentenced to 40 years in prison after being found guilty of murdering her three infant children — Patrick Allen, Sarah Kathleen, and Laura Elizabeth — and the manslaughter of her fourth child — Caleb Gibson. 


The prosecution alleged Folbigg murdered her four young children over a 10-year period between 1989 and 1999 by smothering them during periods of frustration. 

Over the decades, she maintained her innocence — and in recent years, a growing number of scientists began to affirm that she was telling the truth. 

On Monday, June 5, the attorney general of New South Wales, Michael Daley, announced he was issuing an unconditional pardon to Folbigg, immediately releasing her from prison, according to the Australian Academy of Science, which independently advised the investigation.

The pardon hinges on a key discovery that emerged in recent years: a rare genetic mutation in the CALM2 gene.


In October 2018, the genomes of the Folbigg children were sequenced and it was revealed that the two girls, Sarah and Laura, had the CALM2 gene variant. As shown by previous research, the variant of the CALM2 gene affects the way calcium binds to cardiac cells and has been linked to heart arrhythmia and sudden cardiac death. 

Further research found that the two boys had another rare genetic variant in the gene BSN, linked to lethal epileptic seizures in mice.

While these discoveries don’t definitively prove how the children died, they strongly suggest that natural causes were a possible factor, which is what 90 scientists argued in 2021. In the eyes of the court, this evidence is enough to throw “reasonable doubt” on the convictions of Folbigg.


“The prosecution case against Kathleen Folbigg relied heavily on the unlikelihood of all four of her children dying at such young ages of natural causes, supported by reliance on the now-discredited ‘Meadows law’," explains Dr Ben Livings, an Associate Professor of Criminal Law and Evidence and Program Director for Criminal Justice at the University of South Australia. 

"The expert evidence of now-retired British paediatrician Roy Meadow had been used in criminal cases in the UK, to help convict several women of killing their children. He famously said that ‘unless proven otherwise, one cot death is tragic, two is suspicious and three is murder’.” 

Experts suggest this case will have a massive impact on the way science helps to guide criminal cases, calling it a watershed moment in the wrongful convictions of mothers convicted for murdering their babies. 

"This case shows the difficulty the law often has with science. The criminal trial deals in the binary guilty-not guilty. Science is often far less clear-cut,” Dr Livings said.


“Kathleen Folbigg’s conviction has long seemed to many to have been unjust. Her pardon and release from prison raise significant questions for how science and experts should be used in criminal trials."

“Community-based innocence projects are not new... What has been missing, is the ability to apply new scientific discoveries and technology to old cases, to re-evaluate evidence in light of that new knowledge, and provide impartial advice to the justice system," said Associate Professor Jeremy Brownlie, a geneticist from the School of Environment and Science at Griffith University

“One clever idea from the Australian Academy of Science would see the judiciary appoint scientific experts to serve as independent advisors to the courts, who could explain the science and help judges and jurors make decisions based upon the most up-to-date scientific knowledge we have," he noted, adding Australia already relies on independent scientific expertise to make informed decisions and this should extend to the justice system, too.


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