A mother who murdered her two children and stuffed them into suitcases stashed inside a storage locker was on Wednesday sentenced to life imprisonment in New Zealand.

Hakyung Lee, a New Zealand citizen originally from South Korea, was earlier this year found guilty of killing her children in a grisly crime dubbed the country's "suitcase murders".

High Court judge Geoffrey Venning sentenced Lee to life imprisonment with a minimum non-parole period of 17 years, saying she had killed children who were "particularly vulnerable".

The 45-year-old showed little emotion as she sat in court, bowing her head with eyes fixed to the floor as the judge handed down the sentence.

Lee killed her son Minu Jo and daughter Yuna Jo, aged six and eight, in 2018 by lacing their fruit juice with an overdose of prescription medication.

Stricken with grief following her husband's death from cancer, Lee said she had planned to kill herself alongside the children but got the dose wrong.

She wrapped her dead children in plastic bags before stuffing them into suitcases that were then hidden at a suburban storage warehouse on the outskirts of Auckland, New Zealand's largest city.

The bodies sat in storage until 2022, when an unsuspecting family pried open the contents of an abandoned storage locker they bought in an auction.

Police used DNA and other forensic evidence to piece together who the children were, how long they had been dead, and ultimately who had killed them.

Lee, who had long since changed her name and fled the country for her native South Korea, was eventually tracked down and arrested in the port city of Ulsan.

She was extradited to face trial in New Zealand.

The sentencing hearing on Wednesday heard how the murders had left deep emotional scars on Lee's family.

- 'Time bomb of fear' -

"If she wanted to die why didn't she die alone?" Lee's mother Choon Ja Lee said in a statement read to the court.

"Why did she take the innocent children with her?"

Lee's brother-in-law said the children's other grandmother was sick with cancer and still did not know about the murders.

Sei Wook Cho said his "daily existence is a time bomb of fear" the grandmother would find out, according to a statement read to the court.

"It was my late brother's will that I protect them," read the statement.

"They were our hope for the future. This is an ongoing sentence from which I can never be paroled."

The trial hinged not on whether Lee had murdered her children -- which she had confessed to -- but whether she knew her actions were morally wrong.

Her lawyers argued she was not guilty by reason of insanity, her crimes the result of a depressive spiral brought on by the death of her husband in 2017.

A forensic psychiatrist testified for the defence about Lee's mental state, describing depression, suicidal thoughts and a belief that killing her children was the right thing to do.

But the prosecution argued Lee's behaviour was calculated, pointing to her efforts to hide the bodies before fleeing the country.