Anaesthetist killed wife and daughter 'with gas-filled yoga ball'

Khaw Kim-sun apparently left the inflatable ball in the boot of his wife's car, where it leaked out and killed her and her teenage daughter. Photo / 123RF

A bright yellow Mini Cooper sat parked near a bus stop in Ma On Shan, a town in Hong Kong.

It was not raining that day in 2015, but the windshield wipers were scraping against the glass; a passerby later said it appeared that Wong Siew-fung and her 16-year-old daughter had fallen asleep inside the car.

But 45 minutes later, the same witness said, they had not moved. The mother and daughter were rushed to a hospital, where they were pronounced dead.

The account comes from court testimony reported by the South China Morning Post. Prosecutors told Hong Kong's High Court on Wednesday that autopsies later revealed that the two died of carbon monoxide poisoning, though the gas did not appear to be leaking from the vehicle. It apparently came from a yoga ball in the trunk - which, prosecutors said, had been filled with the gas and placed there by Wong's husband, according to the newspaper.

Khaw Kim-sun has pleaded not guilty to two counts of murder. Prosecutors say it was likely that Khaw had not intended to kill his daughter.

When police responded to the scene, the ball was lying deflated in the back of the vehicle.

According to the South China Morning Post, prosecutor Andrew Bruce told the court that Khaw Kim-sun, a 53-year-old anesthesiologist, pumped carbon monoxide into the ball and put it into the vehicle in May 2015 as part of a plan to kill his wife but that "the last thing the accused wanted was for his 16-year-old to die."

Khaw apparently did not expect that his daughter would be in the car at the time. Still, the prosecutor said, "if that person knew what was in the car was carbon monoxide and knew it was a dangerous gas likely to kill you, you can confirm this person had homicide on his mind."

Khaw, who is charged with two counts of murder, pleaded not guilty, according to BBC News.

Prosecutors said that Khaw, a professor at the Chinese University of Hong Kong, had been cheating on his wife with a student and that his wife would not grant him a divorce, according to the South China Morning Post.

So, the prosecutors said, Khaw, with help from his student, devised a plan to kill his wife.

Bruce told the court that Khaw ordered tens of thousands of dollars' worth of carbon monoxide, claiming that he planned to use it in a science experiment. The South China Morning Post reported that when his colleagues saw him pumping the toxic gas into a couple of yoga balls, he apparently told them that he was going to test it on rabbits.

Carbon monoxide is a colourless and odourless but deadly gas that can be found in fumes from fuel, gas stoves, gas fireplaces and other things, according to the Centers for Disease Control and Prevention.

Khaw Li-ling, 16, was in the passenger seat of her mother's car.

At certain levels, the CDC said, it can be poisonous to people, causing headaches, dizziness, confusion and, ultimately, death.

During the police investigation into his wife and daughter's deaths, Khaw apparently told investigators that he took the carbon monoxide-filled yoga balls home to attempt to kill rats, but his housekeeper told authorities there were none.

The South China Morning Post reported that at one point, Khaw even suggested that his daughter may have tried to use the gas in the balls to commit suicide.

The prosecutor called it "a lame lie."

"It is simply not true," Bruce told the court, according to the newspaper.