SYDNEY - An Australian mother jailed for killing her four young children was released on Monday after 20 years behind bars, ending what the authorities called a “terrible ordeal”. 

Ms Kathleen Folbigg was dubbed “Australia’s worst female serial killer” after she was convicted in 2003 of murdering three of her children, and the manslaughter of a fourth.

Prosecutors argued that she suffocated the children, who died between the ages of nine weeks and three years old, but Ms Folbigg has steadfastly maintained that each death was due to natural causes.

In 2021, dozens of scientists from Australia and abroad signed a petition calling for Ms Folbigg’s release, saying new forensic evidence suggested that the unexplained deaths were actually linked to rare genetic mutations or congenital abnormalities.

New South Wales Attorney-General Michael Daley said a year-long inquiry, launched in May 2022, had now established “reasonable doubt” surrounding the convictions.

“This has been a terrible ordeal for everyone concerned, and I hope that our actions today put some closure on this 20-year matter,” he told reporters. 

Ms Folbigg, 55, was released on Monday morning from a prison in Grafton where she had been serving a sentence of at least 25 years. 

“We’ve received confirmation that Ms Folbigg has walked free this morning and that she is in the sunlight, she’s now free from prison,” said supporter Sue Higginson, a Greens politician. 

“It is a massive relief for all of those who have stood by Ms Folbigg.” 

In the absence of firm forensic evidence, prosecutors had argued that it was extremely unlikely four children would suddenly die without explanation.

But retired judge Tom Bathurst, who led the inquiry, said subsequent investigations found medical conditions that could account for three of the deaths.

The four children died between 1989 and 1999.

Mr Bathurst said Sarah and Laura Folbigg possessed a rare genetic mutation, while Patrick Folbigg may have had an “underlying neurogenic condition”.

Given these factors, Mr Bathurst found the death of Caleb Folbigg was also no longer suspicious.

He added that he was unable to accept that “Folbigg was anything but a caring mother for her children”.

Mr Peter Yates, Ms Folbigg’s friend, said he was “absolutely delighted”. 

“What we’re particularly pleased about is that he’s given Kathleen a full pardon,” he told national broadcaster ABC. 

“That means that she’s free to live her life as a normal citizen, and that makes a big difference to her.”

While the pardon lifts Ms Folbigg’s prison sentence, Mr Yates noted she would need to separately apply through the court system to have the convictions overturned, a process that could take “two or three years”. 

The Australian Academy of Science, which helped to spark the inquiry, said it was “relieved” to see justice for Ms Folbigg. AFP