An expert report tendered to the inquiry into the convictions of Kathleen Folbigg for killing her four children claims diary entries that were used to convict her are not admissions of guilt.
A second judicial inquiry is looking at the convictions of Folbigg, 55, for the deaths of Sarah, Laura, Caleb and Patrick, who were all under the age of two.
They died on separate occasions in the NSW Hunter region, between 1989 and 1999.
At her 2003 trial, the Crown maintained Folbigg smothered her children, but she maintains they died of natural causes.
The discovery of a rare gene mutation in her two daughters that causes heart problems and sudden death, has cast doubt on her convictions by some experts, but the mutation has not been found in her two sons.
Witnesses have told the inquiry her sons may have died because of other medical conditions.
There were no signs of injury on the four children and the case against Folbigg when she stood trial in 2003 was circumstantial, relying heavily on her diaries.
The Crown submitted at trial that diary entries in which she talked about her struggle with motherhood were admissions of guilt, but Counsel Assisting, Sophie Callan, SC, has told the inquiry, experts who have since analysed them, disagree.
Psychologists and psychiatrists are expected to give evidence that the diaries were an outlet for a grieving mother, with complex post-traumatic stress disorder, and little social support.
One of them, Joanna Garstang, an expert in sudden unexplained infant death, has submitted a witness report, ahead of her evidence on Friday, stating that Folbigg's diary comments are expressions of "self-blame".
"The expressions of self-blame and guilt in Ms Folbigg's diary fit with those described in the literature or that I have witnessed in my clinical and research practice. I do not consider them true confessions of guilt," Dr Garstang said.
"Ms Folbigg is blaming herself for the deaths, she may be considering that her stress caused the deaths."
In her diary entries, Folbigg wrote that stress made her do terrible things and that she was depressed, angry and upset after she "lost it" with her daughter Laura.
"Scared that she'll leave me now. Like Sarah did. I knew I was short tempered and cruel sometimes to her and she left. With a bit of help," she wrote in January 1998.
In June 1990, Folbigg wrote she had "mixed feelings" about the birth of Patrick and whether she was "going to cope as a mother".
"I often regret Caleb and Patrick, only because your life changes so much and, maybe, I'm not a person who likes change," she wrote.
The inquiry has previously released letters Folbigg wrote from jail about the "black moods" referred to in her diaries.
More than 100 pages of letters tendered were written to her friend, Tracy Chapman.
In a letter dated February 2005, Folbigg wrote: "While my name is attached to words like 'serial killer', I have no hope of ever being heard fairly or otherwise."
In May the same year, she wrote that her diary entries "sounded atrocious" because she was not in a positive frame of mind.
Folbigg explained the "black moods" she referred to in her diaries was her depressive state.
"Not black as in evil, or nasty or murderous. Just dark as in the colour black," Folbigg wrote.
"The (diaries) were used to 'dump' every negative emotion, feeling, thought, I ever had."
Folbigg has five years left to serve of her 25-year sentence.
The inquiry continues before retired Chief Justice Tom Bathurst, KC.
