Reginald Blanch QC, the former NSW District Court chief judge who presided over the inquiry, concluded he had no reasonable doubt as to the child killer's guilt in a report published on Monday night.

Folbigg was jailed in 2003 for at least 25 years for murdering her children Patrick, Sarah and Laura - aged from eight months to 19 months - between 1991 and 1999.

She was also found guilty of the manslaughter of her first child, Caleb, who was 19 days old when he died in Newcastle in 1989.

The 52-year-old has maintained her innocence, claiming all four children died of natural causes.

But Mr Blanch's report on Monday said "the only conclusion reasonably open is that somebody intentionally caused harm to the children, and smothering was the obvious method".

"The evidence pointed to no person other than Ms Folbigg," the report said.

Folbigg's evidence and listening device transcripts - which weren't before the jury at trial - showed she had been untruthful, unbelievable and "made deliberate attempts to obscure the fact that she had committed the offences", it said.

The inquiry was announced by NSW Attorney-General Mark Speakman in 2018 after Folbigg's lawyers lodged a petition casting doubt on some evidence that led to her conviction.

At the time, the attorney-general said he'd formed the view it was necessary "to ensure public confidence in the administration of justice".

On Monday, Mr Speakman said he'd spoken with Craig Folbigg - the babies' father and Folbigg's ex-husband - regarding the report.

"I acknowledge that the decision to commence an inquiry has further aggravated what already was an unimaginable tragedy," he said in a statement on Monday.

"I am sorry for the toll that the inquiry has taken on Mr Folbigg and family members over the last year."

He said he hoped the findings "might provide comfort in some way to the relatives of Caleb, Patrick, Sarah and Laura, and will dispel community concern regarding Ms Folbigg's convictions".

Folbigg's lawyer Stuart Gray in his response to the report said they were disappointed, but looked forward to NSW Governor Margaret Beazley's consideration of the transcript and report.

"Ultimately, it is a matter for the governor to dispose of Ms Folbigg's petition," he said in a statement.

"We remain hopeful that consideration will be given to the evidence of the various experts that appeared at the inquiry and those that submitted reports after it."

Mr Speakman says he will recommend to the governor that no further action be taken.

Craig Folbigg's brother, John, previously described the inquiry as "most unnecessary and most definitely unwelcome".

"However we have endured it as ultimately it would, we feel, help to ensure that the justice that Caleb, Patrick, Sarah and Laura received in 2003 is upheld," he said in May.

Under Folbigg's 30-year maximum sentence, she will be eligible for parole in 2028.

Australian Associated Press