Kathleen Folbigg has told an inquiry into her convictions she believed a supernatural power took three of her four children away.

Caleb, Patrick, Sarah and Laura all died in the decade from 1989, aged between 19 days and 19 months.

Folbigg was jailed for at least 25 years in 2003 after being found guilty of killing them.

In an October 1997 diary entry, when Laura was two months old, Folbigg wrote: “Wouldn’t have handled another like Sarah. She saved her life by being different.”

The 51-year-old mother gave evidence at the New South Wales coroners court on Tuesday that a belief was “ingrained” in her that there were “things going on beyond my control”.

“‘She saved her life by being different’ is my hope and dream that Laura being different would have saved her life. But in the end, it didn’t,” Folbigg said.

Former NSW district court chief judge Reginald Blanch QC, who is presiding over the inquiry, asked: “Are you saying to me that you believed that there was some supernatural power that took the other three children away from you, and you were concerned that that same supernatural power would take Laura away from you, and that she saved her life by being different on that basis?”

Folbigg replied: “Yes, along those lines.”

She denied suggestions put to her by barrister Margaret Cunneen SC, representing her ex-husband Craig Folbigg, that “homicidal rages” or “psychological mood swings” made her smother her babies to death.

She said a January 1997 diary entry about having done “terrible things” due to stress did not mean she had killed her first three children.

“It’s a broad spectrum of things that I am using the word ‘terrible’ for,” she said on Tuesday. “It could be me placing my child down to let her cry for even 30 seconds – that’s a terrible thing, in my view.”

But Cunneen noted Folbigg described her father’s murder of her mother as “selfish and unthoughtful” and “a stupid mistake” in other entries.

When Folbigg questioned the relevance of that comparison, her ex-husband’s barrister said she was trying to get “into her lexicon” and use of words.

Folbigg said she believed her moods affected “everything” including her children who “died and decided they didn’t want to be with me anymore”.

Cunneen said: “Of course, you know, that babies don’t decide whether or not to live?”

Folbigg replied: “At that stage in my life, I did not know that.”

“My concerns were almost paranoia.”

Folbigg in February 1997 wrote: “My guilt of how responsible I feel for them all haunts me. My fear of it happening again haunts me.”

She rejected Cunneen’s suggestion she only felt guilty because the children died at her hands.

Earlier on Tuesday, Folbigg was asked questions about a diary entry four months after the death of her fourth baby in which she wrote she hoped her diary would not “come back to bite” her like another had.

“That’s a reflection on the fact that the previous diary had been used in the manner that it had been used,” she said under cross-examination.

Cunneen asked: “As evidence of the truths that are contained within it?”

“As evidence of using someone’s thoughts in a manner that didn’t seem appropriate, as far as I’m concerned,” Folbigg replied.

Six of her diaries taken from the period in which the children died are before the inquiry, used by prosecutors in past court proceedings, while up to five others are unaccounted for.

Folbigg recalls throwing one of them out but on Monday denied it was because it contained significantly incriminating material.

“I didn’t kill my children and these diaries are a record of just how depressed and how much trouble I was having and all of the issues that go with that,” she said.

Continuing her evidence on Tuesday, she told Cunneen that she had treated the diaries as if she was writing to a close friend and signed them off as “Kathy”.

In November 1997, Folbigg wrote: “With Sarah all I wanted was her to shut up, and one day she did.”

The following month, she wrote: “Laura’s a fairly good-natured baby, thank goodness. It has saved her from the fate of her siblings.”

Laura died in March 1999.

Cunneen cited a July 1999 entry in Folbigg’s diary which reads: “I just pray it doesn’t come back to bite me like my ’97 one has.

Folbigg denied hiding one diary – later found by police – within a crocheted bag, wrapped in clothes and inside a blue container in her wardrobe.

Her evidence continues.

Blanch will prepare a report on its results for the NSW governor.