Attorney General Mark Speakman announced on Wednesday he had recommended NSW Governor Margaret Beazley direct a second inquiry into the 2003 convictions for the murder of Folbigg's children Patrick, Sarah and Laura, and manslaughter of son Caleb.

She is currently serving a 30-year prison sentence with a non-parole period of 25 years, which ends in 2028.

The recommendation came after the Governor received a petition in March last year from Folbigg's lawyers asking for a pardon based on scientific evidence of a gene mutation that they argue may explain the daughters' deaths.

NSW Hunter region woman Helen Cummings, of Newcastle, has long advocated for Folbigg's release.

She was hoping Mr Speakman would refer the matter back to the Court of Criminal Appeal and said she felt sad Folbigg would go through another public inquiry.

"The Court of Criminal Appeal appeal has the power to exonerate her," Ms Cummings said.

"After today she's still in jail, this is a thing we have to face. She's still languishing in a prison cell. There will be another whole episode with another inquiry. He could have pardoned her."

However she said she was pleased Mr Speakman had "left a door open" and thought his words indicated he was receptive to the evidence.

"I'm hopeful," Ms Cummings said. "I spoke to Kathleen yesterday, she will soldier on."

The matter has had several unsuccessful appeals to the Court of Criminal Appeal, a number of applications to the High Court, a public inquiry in 2018-2019, and in relation to that inquiry's findings, a discontinued application for special leave to the High Court following a judicial review by the Court of Appeal.

Mr Speakman said he could "understand why members of the public may shake their heads and roll their eyes in disbelief about the number of chances that Folbigg has had to clear her name", but believed the evidence reached the "necessary threshold for some kind of intervention".

A pardon wasn't appropriate, he said, because the evidence needed to be tested. A pardon also wouldn't quash the conviction.

He said a public inquiry "is more likely to get to the bottom of this scientific evidence than an adversarial process before the Court of Criminal Appeals".

Mr Speakman said it was a difficult decision, and apologised to Folbigg's ex-husband Craig and his family for the "retraumatisation".