Warning: This story contains graphic and potentially distressing details that may upset some readers.
Crown prosecutors in the murder trial of the woman charged with killing her three young daughters believe the mother had grown "jealous and resentful" of her children.
The revelations came during a grim opening day at the Christchurch High Court, as 42-year-old Lauren Anne Dickason appeared in the dock in front of Justice Cameron Mander.
Dickason is alleged to have taken the lives of her two-year-old twin daughters Karla and Maya and their older sister Liane, at their Timaru home on 16 September 2021.
She has pleaded not guilty, with the defence to argue insanity and infanticide.
But the Crown argued there was no medical defence for what Dickason is accused of doing.
Prosecutor Andrew McRae told the court Dickason made an unsuccessful attempt to asphyxiate the girls, before smothering them after her husband left home to attend a work function.
Details of the alleged murders had been suppressed until now. Other details of the night's events were too graphic to publish.
The court heard Dickason had grown resentful of her children because of the effect on her marriage, following a period where she struggled with mental health issues.
"Throughout all of this time, [Dickason] would often lament to her closest friends on the considerable impact on her ability to do things, but most importantly on her relationship with her husband Graham," McRae said.
"She would comment that they had little time together and this caused her stress. She felt the children favoured Dr Dickason and the Crown say she was resentful of that."
McRae said Dickason "snapped" the night she killed her daughters, angry they had jumped on the couch and were not listening to her.
He added that her perfectionist nature also clashed with the unpredictable nature of raising children.
"The anger was bubbling over from many aspects of her life, the ongoing behaviour of the children. But also the Crown says she was resentful of how they stood in the way of her relationship with her husband."
Dickason, who later sat at the counsel's table, appeared tearful during the Crown's opening.
The defence for the woman who killed her three children in Timaru has told the court that she loved and cared for her children.
Defence lawyer Kerryn Beaton KC said in her opening statement that Lauren Dickason longed to be a mother, and underwent 17 rounds of IVF to have her daughters.
Dickason loved her children, Beaton told the court.
She said Dickason had always tried to do what was best for her children, but on September 16 2021 she was experiencing such a major depressive episode that she felt she needed to kill herself, and take her daughters with her.
In his opening remarks, Justice Mander told jurors the defence of infanticide could lessen culpability if the effects of childbirth had left a mother mentally disturbed.
"Our law provides where a woman causes the death of her child in a manner that would otherwise amount to murder, where at the time the balance of her mind was disturbed by reason of a disorder, consequent upon childbirth to such an extent she would not be held fully responsible."
Infanticide functions as both a standalone offence and as a partial defence to murder, according to the Crimes Act.
Justice Mander said to what point the mental disorder impacted Dickason's sense of morality would be argued.
"The nixed element of insanity is likely to be an issue, that is whether this disease of the mind caused Mrs Dickason, at the time, to be incapable of knowing her actions were morally wrong, having regard to commonly accepted standards of right and wrong."
Graham Dickason is the first of 30 witnesses who will give evidence via audio link on Tuesday morning. The trial is set down for three weeks.