Kathleen Folbigg is “walking … outside … in the sunshine” after being freed after 20 years in a NSW jail, a supporter says.

It came as questions arose about whether Ms Folbigg will seek to have her convictions quashed, and a supporter flagged a likely bid for compensation for her two decades in prison over the deaths of her four young children.

Ms Folbigg was released from Clarence Correctional Centre at Grafton on Monday, after being pardoned.

NSW Attorney General Michael Daley said he had received an advance copy of a summary of an inquiry by former NSW chief justice Thomas Bathurst into Ms Folbigg’s convictions that found there was reasonable doubt about her guilt.

“There is a reasonable possibility that three of the children died of natural causes,” it said.

Mr Daley told a packed media conference on Monday that Mr Bathurst was “unable to accept… the proposition that Ms Folbigg was anything but a caring mother for her children”.

He recommended to NSW Governor Margaret Beazley that Ms Folbigg – once dubbed Australia’s worst female serial killer – be pardoned. Ms Beazley accepted the recommendation.

“She has now been pardoned,” Mr Daley said.

“Justice can ultimately be done even it takes a long time”, he said.

Shortly after Mr Daley’s announcement, Greens MP and supporter Sue Higginson said Ms Folbigg had left jail.

“She’s walking, she’s outside, she’s in the sunshine… justice has been done,” she said.

“This is our Lindy Chamberlain case here in Australia,” Ms Higginson said indicating that Ms Folbigg would pursue compensation for the “20 years of her life that has been lost”.

Ms Folbigg, now 55, was expected to spend the night with lifelong friend and advocate Tracey Chapman at her home in the NSW northern rivers. Ms Chapman reportedly met Ms Folbigg at the jail gates on Monday.

“Tracy has a bed made for her and that’s where she’ll be sleeping tonight,” Ms Higginson said.

The dramatic developments came 20 years after the jury in a seven-week trial found Ms Folbigg guilty of killing her four babies – Caleb, Patrick, Sarah and Laura – between 1989 and 1999.

After being found guilty of three counts of murder and one of manslaughter in 2003, Ms Folbigg was sentenced to 30 years in jail. She had not been not eligible for parole until 2028.

Monday’s pardon does not mean Ms Folbigg’s convictions will automatically be quashed.

“The only body that can do that is the Court of Criminal Appeal,” Mr Daley said.

Ms Folbigg has always maintained her innocence.

Ms Higginson said she believed the convictions would be quashed in court, and pointed towards an admission from the director of public prosecution about reasonable doubt.

“That means that most likely there will be no objector in terms of her application to have her convictions quashed in the criminal court of appeal,” she said.

“The sooner that [Mr Bathurst’s] findings are on paper, the sooner that application is before the Court of Criminal Appeal, the sooner the next step of justice for Kathleen Folbigg can commence.”

In April, an inquiry into Ms Folbigg’s convictions heard credible evidence her four children may have died of natural causes.

Rare genetic variants identified in Folbigg and her daughters triggered the second inquiry into her conviction not long after a 2019 examination.

Ms Higginson indicated Ms Folbigg would also seek compensation or an “ex gratia payment of some sort”.

“Whatever that sum looks like may be the biggest sum that we can imagine,” she said.

Mr Daley said on Monday he had also spoken to the children’s father and Ms Folbigg’s former husband, Craig Folbigg.

“I am thinking of him today as well,” he said.

“It will be a tough day for him.”

Mr Folbigg and his family are yet to make any public comment on Monday’s developments.

Mr Daley said the long-running case had been an ordeal for all involved.

“We’ve got four little babies who are dead, we have a husband and wife who lost each other, a woman who spent 20 years in jail and a family that never had a chance. So you’d not be human if you didn’t feel something about that, would you?” he said.

“I hope that our actions today put some closure on this 20-year-old matter.

“I am grateful as well, and all citizens should be, that the review provisions are available in NSW to ensure that where circumstances arise like these ones justice can be ultimately done, even if it takes a long time.”

-with AAP