Two children were given juice laced with prescription drugs before their mother wrapped their bodies in plastic bags and placed them in suitcases, a court has heard.
Warning: This article contains details that may be distressing for some readers.
Hakyung Lee has been charged with killing her children, eight-year-old Yuna Jo and six-year-old Minu Jo, sometime in 2018.
Their remains were found when the suitcases were sold at auction by an Auckland storage facility after payments lapsed in mid-2022.
Ms Lee was later arrested and extradited from South Korea to face murder charges.
Ms Lee, who is defending herself with the assistance of two stand-by counsel, has admitted killing her children but claims she is not guilty by reason of insanity.
Both the defence and the Crown presented their closing arguments to the jury in Auckland's High Court on Monday, local time.
Killing children 'selfish', not 'altruistic', jury hears
The murder of Ms Lee's children, Crown prosecutor Natalie Walker told the jury, was not an "altruistic" act.
Ms Lee's stand-by counsel had said she feared the children finding her if she took her own life, and did not want them to live without both parents.
Her husband, Ian Jo, died of cancer in late 2017, more than six months before the children's deaths.
"Sometimes we can never know why people do the things they do," Ms Walker said.
"Perhaps the thought of a life parenting her children alone without her husband was too much for Ms Lee.
"She was dependent on him, [and] at least socially isolated.
"When he died, the steps she took from the 27th of June onwards are consistent with her wanting a new life on her own and a new name."
Ms Walker alleged Ms Lee had lied "on numerous occasions" about attempting suicide both before and after killing Yuna and Minu.
"The Crown suggests that when she gave her two young children nortriptyline, it was a selfish act to free herself from the burden of parenting alone," Ms Walker said.
"It was not the altruistic act of a mother who had lost her mind and believed it was the right thing to do; it was the opposite."
She asked the jury to consider whether the timing of events was consistent with someone not criminally responsible, noting Ms Lee acknowledged killing her children.
"She accepts that after they died, she alone was responsible for wrapping each of her children in three layers of plastic bags," Ms Walker said.
"Each of which she tied with a knot before putting them into a suitcase. Each of which she locked, wrapped in a further plastic bag, and sealed with duct tape.
"And finally, she accepts that she alone was responsible for taking the suitcases to Unit 456 of the SafeStore facility in Papatoetoe, which she did in two trips on the 30th of June 2018."
Ms Lee's actions, Ms Walker said, showed "considerable effort", noting diagrams of each suitcase.
"It's quite unimaginable, actually, members of the jury, it's quite unimaginable," she said.
"And yet that's what she did. This diagram tells you, that's what she did to each of her children.
"It would have required real planning, real care, real determination … and real effort."
Details of children's last moments before murder
When his remains were found, six-year-old Minu was wearing a pair of underwear with the word Wednesday on the front.
The pair were part of a set labelled with the days of the week, bought for him by his mother in March.
Ms Walker told the jury it was just another sign of when the children may have been killed.
"We don't know whether he wore these days of the week underwear on the right days or not," she said.
"He was a six-year-old boy.
"However, I suggest it's a small piece of evidence which, when viewed in light of all the other evidence, could well suggest Minu did wear the days of the week underwear according to which day it was.
"And that Ms Lee did take her children's lives on Wednesday the 27th of June 2018."
Both children were found wearing long-sleeve T-shirts and puffer jackets, according to the medical examiner.
The jury was also reminded of what the Crown said is the best evidence of the children's last moments.
On June 27, 2018, a PlayStation in the home recorded activity by users "HeroMinu" and "PrincessYuna", updating Minecraft trophies.
"[Ms Lee] said she gave the children the medication," Ms Walker said, referencing testimony by defence witness Yvette Kelly.
"She said she dissolved that in fruit juice and that the children consumed that without [issue].
"The children drank the juice and then they became drowsy from the medication and they toddled off to their own beds … and went to sleep there and then."
Over the following days, the Crown alleged Ms Lee changed her name, passed a driving test, bought plastic bags, went to a salon, and began making arrangements to leave the country.
Court hears of downward spiral 'into hell' after husband's death
In closing, Ms Lee's stand-by counsel Lorraine Smith detailed a months-long spiral from a "happy family" to isolation and mental illness.
Ms Lee, she said, had been left without proper support and was suffering extreme mental health issues at the time of her children's deaths.
"There is an indisputable descent from being a mentally well woman to a woman with mental illness," she said.
She described Ms Lee as someone who was "not resilient" and who relied on other people for balance.
She noted Ms Lee had developed a pattern of mental illness in the wake of her father's death when she was just 18 years old.
"Her husband, Ian, was everything that she needed; he was the positive to her negative," Ms Smith said.
She added Yuna and Minu had been born into a "happy, loving environment".
"[Ms Lee] was coping well during this golden period," Ms Smith said.
"But then Ian became ill and died … and this began her descent into hell.
"She dealt with six months of [his] illness, she stayed with the children while Ian made a final attempt to go to Korea and get some treatment.
"But he comes back in a shocking state, and [Ms Lee] does not want the children to see their father like that."
It was at this time, the court heard, Ms Lee began to "irrationally" believe the answer was to kill herself and her children.
Earlier this month, Ms Lee's mother told the court her daughter had repeatedly mentioned a wish to be with her husband in death.
By May 2018, Ms Lee had cut off contact with all family and friends, and the children were no longer attending school.
Ms Smith rejected the Crown's claim Ms Lee planned to kill the children to start a new life in South Korea.
Her decision to change her name, Ms Smith said, was not an attempt to create a new identity, but a reflection of her Korean heritage and "superstition".
She also rejected the use of the children's PlayStation data as showing their last day alive.
"We cannot know what was the last time the children played a game, because there is no log for game activity for June 2018," she said.
"The evidence suggests there was no significant gameplay after the 6th of June, just updates.
"We need to be very careful before filling in the gaps of evidence."
Judge Geoffrey Venning told the jury he would summarise the case for them on Tuesday morning, before leaving them to deliberate.
