SYDNEY, June 6, 2023 (BSS/AFP) - A mother once dubbed Australia's "worst female serial killer" will now fight to erase her convictions, her lawyers said Tuesday, after she won a landmark pardon and was released from prison this week.

Kathleen Folbigg was in 2003 convicted of killing her four infant children, who separately died without explanation between 1989 and 1999.

The 55-year-old was imprisoned despite a lack of forensic evidence linking her to the deaths, and steadfastly maintained her innocence during her 20-year incarceration.

In recent years scientific breakthroughs have uncovered genetic mutations that helped explain why some of the children died, paving the way for Folbigg to be released from prison on Monday.

She was pardoned by New South Wales Governor Margaret Beazley after a long-running inquiry concluded there was "reasonable doubt" she had killed her children.

Although she has won her freedom, Folbigg must now go through a separate legal process to have her convictions officially overturned.

Folbigg's lawyer Rhanee Rego said Australia's court system had "failed her at every step", and it had taken authorities far too long to reopen the case.

"If Australia really wants to make some good from a tragic story, they'll seriously consider reviewing the system of post-conviction review," she told reporters.

"Instead of trying to understand why her children died, potentially through an inquest... we threw her in jail, locked her up, called her Australia's worst female serial killer.

"We, as her legal team, will stand strong with her and stand with her all the way along to make sure her name is cleared and right is done by her," Rego added.

- 'Bamboozled' -

The Australian Academy of Science, which played a crucial role in the Folbigg inquiry, described the convictions as "Australia's greatest miscarriage of justice".

"What this case has absolutely shown is there's an absence of a mechanism for the justice system to consider new information, particularly scientific information," chief executive Anna-Maria Arabia told national broadcaster ABC.

Folbigg was on Monday morning released from a prison in Grafton, in the north of New South Wales state, where she had been serving a sentence of at least 25 years.

Long-time friend Tracy Chapman said Folbigg was now slowly getting her head around the wonders of modern technology, such as smartphones and on-demand television.

"She slept for the first time in a real bed, had a cup of tea in a real crockery cup, real spoons to stir with," Chapman told reporters.

"That sounds basic to you all, but she's grateful.

"The phones have bamboozled her a bit. Even the television she was going, 'Oh my god, it's got so many capabilities'."