The trial for a woman accused of murdering her three children at their Timaru home will begin tomorrow in the High Court.

Lauren Anne Dickason has pleaded not guilty and will mount a defence of insanity and infanticide at the trial - set down for two weeks before Justice Cameron Mander and a jury in Christchurch.

Dickason allegedly killed six-year-old Liane and two-year-old twins Maya and Karla at their Timaru home on September 16, 2021.

Her husband, orthopaedic surgeon Graham Dickason, found the three children dead and his wife in a serious condition when he arrived home after having dinner with colleagues.

Graham and Lauren Dickason with their daughters before the alleged murders. Photo / Facebook

The family had emigrated to New Zealand from Pretoria, South Africa and had only been in Timaru two weeks - following a stint in MIQ - when the children died.

The specific details of their deaths have been suppressed but may be published as the trial opens.

Dickason first appeared in the Timaru District Court two days after the alleged murders.

After a brief hearing, she was remanded in custody to the medium secure psychiatric unit at Hillmorton Hospital and has remained there since.

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Dickason is represented by Kerryn Beaton KC, who is expected to call three defence experts agreeing at the time the children died, their mother was suffering a significant mental disturbance and therefore is not criminally culpable.

The Crown case, led by Timaru Crown solicitor Andrew McRae, is that Dickason was not insane at the time, that the girls were murdered, and that she is criminally responsible.

The jury will be empanelled from 10am and McRae will open the Crown case.

Beaton is also expected to make an opening statement on behalf of her client.

The trial will then continue for about two weeks.

Alongside the psychiatric experts, the jury is expected to hear from a number of other witnesses including Graham Dickason and other family members, as well as police who worked on the triple homicide investigation.

After the three girls were found dead, Dickason was rushed to Timaru Hospital in a critical condition.

Within 24 hours, she had been arrested and charged with the three murders.

A week after the alleged murders, Graham Dickason said he had forgiven his wife and felt she was also a victim in the tragedy.

He has since returned to South Africa but has visited New Zealand at least once.

Details of any funeral or farewell for the children have not been shared by the family.