Kathleen Folbigg was no stranger to tragedy when all of her children died before their second birthdays.
Named after her mother, she was born Kathleen Donovan in 1967, and had a traumatic start to life.
Before her second birthday, her father fatally stabbed her mother to death in Sydney's inner west, leaving Ms Folbigg in the care of the state.
She was raised by adoptive parents in Newcastle, in the New South Wales Hunter Region, where she met lifelong friend Tracy Chapman, who is now her next of kin.
Ms Chapman, along with fellow school friends Billi-Jo Bradshaw and Megan Donegan, have stuck by their friend to this day.
Four dead babies
In 1985, aged 18, Kathleen met Craig Folbigg, and the pair married two years later.
The couple had their first of four children, a boy named Caleb, in 1989.
But at just 19 days old, Caleb was found dead in his bassinet.
Two years later, their second son Patrick died, aged eight months.
In 1993, their daughter Sarah died at 10 months.
Then, more than five years later, their second daughter Laura died at 18 months old.
Following their deaths, in May 1999, Craig Folbigg handed his wife's private diaries over to police.
Those diary entries would form the basis of the prosecution case against her.
The following year, Craig and Kathleen Folbigg formally separated.
In April 2001, Ms Folbigg was charged with four counts of murder, accused of smothering all of her children to death.
She pleaded not guilty, and claimed they died of natural causes.
Ms Folbigg stood trial in Sydney's Supreme Court in April 2003, where the jury were shown entries from her diaries.
The prosecution claimed they were admissions of her guilt.
Penned throughout her child-rearing years, Ms Folbigg wrote "my guilt about them all haunts me", "what scares me most will be when I'm alone with the baby" and "obviously, I'm my father's daughter".
After a seven-week trial, a jury found Ms Folbigg guilty of the murders of Patrick, Sarah and Laura, and the manslaughter of Caleb.
From that day on, she became known around the world as Australia's worst female serial killer.
She was initially sentenced to 40 years jail with a 30-year non-parole period, which was reduced on appeal to 30 years, with a non-parole period of 25.
Ms Folbigg always maintained she was innocent.
But her former husband and the father of her children, Craig, turned on her, telling reporters outside court of his relief the jury found her guilty.
"My most humble thanks go to 12 people who I've never formally met, who today share the honour of having set four beautiful souls free to rest in peace," he said.
Her adopted sister Lea Bown also believed she was a murderer.
"She's definitely guilty, those four children should be here now," Ms Bown said in 2014.
'Justice for Kathleen Folbigg'
While her family turned their backs on Ms Folbigg, her longtime friends, including Ms Chapman, mounted a campaign to clear her name.
It was a crusade they dubbed "Justice for Kathleen Folbigg".
Ms Folbigg languished in jail for more than a decade until 2015, when NSW Governor David Hurley received a petition to review her convictions based on forensic pathology findings.
The petition prompted an inquiry into her convictions three years later, where new scientific evidence was first presented.
That evidence included a gene variant shared by Ms Folbigg and her two daughters, which may cause cardiac arrhythmia and sudden death.
The same variant was not found in Caleb or Patrick.
Despite the new medical discovery, the judge found in July 2019 the evidence "as a whole" only reinforced her guilt.
Worldwide scientific support
A breakthrough was on the horizon.
Two years later, 90 scientists from around the world signed a petition handed to NSW Governor Margaret Beazley, calling for Ms Folbigg to be pardoned.
The petition was based on an international study, which found an arrhythmia syndrome was a reasonable explanation for the death of the Folbigg girls, while the two boys carried different gene variants shown to cause life-threatening early-onset epilepsy in mice.
That prompted a second inquiry, this one fronted by former NSW Chief Justice Tom Bathurst, which began in November 2022.
When the hearings concluded in April this year, a lawyer for the Director of Public Prosecution conceded there "was" reasonable doubt that Ms Folbigg murdered her children.
All that was left for Ms Folbigg to do was to wait for the findings.
While the entire document has not been released, preliminary findings, released on Monday, have freed Ms Folbigg after 20 years in prison.
