Inquiry into Kathleen Folbigg’s children’s deaths questions genetic mutations

A genetics expert who believes Kathleen Folbigg’s children most likely died from natural causes warns there’s not enough science to prove how they died.

A genetics expert who found the babies of infamous child killer Kathleen Folbigg most likely died from natural causes has warned the inquiry into the mother-of-four’s convictions that there might be no distinct answer as to how the babies died, due to a lack of scientific research.

Folbigg, 55, was found guilty of three counts of murder and one of manslaughter in 2013 after her babies Patrick, Sarah, Laura and Caleb died in suspicious circumstances between 1989 and 1999.

She has consistently denied wrongdoing and is serving a 30-year prison term with a 25-year non-parole period. She is not eligible for parole until 2028.

Kathleen Folbigg’s innocence is being questioned for a second time before an inquiry into the deaths of her four children.

Despite multiple appeals, Folbigg has failed to clear her name. A public inquiry in 2018 also reinforced her guilt.

In 2021, the emergence of new expert medical evidence – appearing to show Sarah and Laura Folbigg carried a genetic mutation that could cause sudden death and cardiac problems – led to renewed calls for another probe into the case.

Former NSW chief justice Tom Bathurst KC is heading the second inquiry into Folbigg’s convictions and is considering whether there is reasonable doubt about her guilt.

Caleb Folbigg.

Patrick Folbigg.

Professor Peter Schwartz told the inquiry on Wednesday it was “very naive” to come to an absolute conclusion about the cause of death of the four children.

He said while a report he co-authored found the babies had most likely died from a mutated variant which caused cardiac arrest, it would be premature to rule out any other possibility because of a lack of evidence.

“It’s dangerous to suggest that the variants only produce particular phenotypes, so in the present case, even though the children didn’t represent with what might be ‘typical phenotypes’ it would be dangerous to conclude the death was attributed to the particular variant,” Professor Schwartz said.

“When we’re hearing testimony in a trial as important as this one, we have to be careful with what we say.”

Mr Bathurst asked Professor Schwartz whether it was “dangerous to conclude the deaths were attributed to the particular variant” when “working on the assumption that there’s no other explanation”.

Professor Schwartz explained the report came to its ultimate findings based off the evidence available but that doesn’t mean future scientific resources could provide greater insight.

“I’m not making any suggestions what killed the two girls; these mutations are providing a very valid and medically sufficient explanation,” Professor Schwartz stated.

“I see history repeating itself, that’s why I’m asking to be very careful when making statements that could be proven wrong in a short while.”

Mr Bathurst accepted this but stated his “difficulty” was that he didn’t have time to wait for the science to discover other cases of the variant, which the inquiry heard could take years.

Kathleen Folbigg with her baby daughter Sarah before the infant died on 30 August 1993.

Earlier on Wednesday, Counsel assisting the inquiry, Sophie Callan SC, asked Professor Carola Vinuesa if her evidence was unconsciously biased because of her public support of Folbigg’s innocence.

The inquiry was told Professor Vinuesa had retweeted a link to a petition to free Folbigg and media reports where she showed her support for the convicted child killer.

One of the tweets Professor Vinuesa posted included statements about how she found it “very, very sad that Kathleen will spend another Christmas in prison despite all the evidence” her children died of natural causes, the inquiry heard.

“I think I’m entitled to have an opinion, my opinion is an extension of my science,” Professor Vinuesa said.

“I believe I’m free to have my opinion but it’s predominantly because I believe in my science.

“The evidence I have provided cannot be manipulated … the genetic evidence is there”.

Mr Bathurst told the inquiry he accepted Professor Vinuesa’s explanation stating there’s “nothing wrong” with her expressing her own personal views but he wanted her to clarify whether it had given her a “perverse view” of other experts’ differing findings.

She rejected this stating that she always “separates my personal opinions from my scientific work”.

“I am allowed to feel empathy,” Professor Vinuesa said.

“If I’m convinced of my science then the logical thinking is that she shouldn’t be in prison.

“When you appointed me to this inquiry, you were aware of me having expressed these views.”

Professor Vinuesa told the inquiry on Wednesday that genetic analysis was constantly evolving because rare mutations were hard to come by in order to compare with existing gene sequences.

She had contributed research on the rare mutation CALM2G114R and hypothesised that the four Folbigg children most likely died from this variant that caused cardiac arrest.

Sarah Folbigg.

Laura Folbigg.

She explained Sarah and Laura had this variant and it was concluded the boys also died from similar issues relating to the sudden unexplained deaths.

Mr Bathurst asked the professor about the criticism of her findings that the report “assumed the cause of death is the genetic variant because they had the genetic variant”.

Professor Vinuesa said the paper “assumed there was a genetic cause” to begin its analysis.

“We assumed it was one of the two most common cause of death,” she said.

“If you start a genetic exercise, you have to say what the most possible causes for this (are).”

Professor Vinuesa said it was “partially fair” to state it was impossible to draw any inference into what caused the deaths.

She explained the ongoing discovery of new genomes continued to widen the scientific understanding of mutations.

Professor Vinuesa said even a power-point presentation she had handed over to the inquiry on Friday to use during her evidence needed to be updated because a new research paper released on the weekend had answered one of her questions about the mutations.

The inquiry continues.

Originally published as Inquiry into Kathleen Folbigg’s children’s deaths questions genetic mutations