Professor Charged With Killing Family With Yoga Balls

The bodies of Wong Siew-fung and Khaw Li-ling were found in their car in May 2015, after they died from carbon monoxide poisoning.

Malaysian professor Khaw Kim-sun has faced the Hong Kong High Court, charged with murdering his wife and daughter with a yoga ball filled with carbon monoxide.

Police prosecutors have alleged Khaw put a carbon monoxide-filled yoga ball in the boot of his wife's car, slowly poisoning Wong Siew-fung and their daughter Khaw Li-ling as the toxic gas leaked through the plastic.

It is alleged Khaw killed his wife because he was having an affair with one of his students, and his wife refused a divorce despite knowing of the affair.

It is believed Khaw did not know his 16-year-old daughter was home from school, and did not intend to kill her.

Khaw Li-ling, 16. Image: Handou

The bodies of Wong Siew-fung and Khaw Li-ling were found in their locked Mini Cooper by a jogger, Tong Yuk-Ling, in May 2015.

Tong told the court the windscreen wipers had been on although it was not raining, and it looked as though they were asleep, reported the South China Morning Post.

However after they had not moved for 45 minutes police were notified, with the two rushed to the Prince of Wales Hospital -- where Khaw worked as a doctor--  but they were pronounced dead.

The initial circumstances surrounding their deaths were a mystery to investigators, with just the deflated yoga ball was found in the car boot.

An autopsy of the bodies revealed they had died of carbon monoxide poisoning, and police began investigating the yoga ball after car defects were ruled out.

Khaw Kim-sun arrives at court in a prison van. Image: Getty Images

Colleagues of Khaw saw him fill two yoga balls with the toxic gas at the Chinese University's Department of Anesthesia and Intensive Care, where he worked.

Khaw had allegedly told his colleagues he was testing the purity of the carbon monoxide on rabbits for a research project, Police Prosecutor Andrew Bruce told the court.

Bruce told the court Khaw had used a metre in his car as he transported the gas-filled balls home, to ensure he was not poisoned himself.

It is also alleged in police interviews Khaw told investigators he had taken the carbon monoxide to treat a rat infestation in his home, however a domestic helper testified in court their home did not have a rodent problem.

The domestic helper working for the family of Malaysian national Khaw Kim-sun who is accused of murdering his wife and daughter, leaves after testifying. Image: Getty Images

He also suggested his daughter Khaw Li-ling had used the toxic gas to commit suicide, but this suggestion was ruled out by Bruce.

Khaw has pleaded not guilty to the two charges of murder. The trial continues.