In this Aug 23, 2018 photo, a prison van carrying Malaysian professor Khaw Kim-sun, who is accused of murdering his wife and daughter, leaves the High Court in Hong Kong. (PHILIP FONG / AFP)

HONG KONG – A Malaysian professor based in Hong Kong was sentenced to life imprisonment on Wednesday for murdering his wife and daughter with a yoga ball full of carbon monoxide.

The sentence of Khaw Kim Sun, associate professor of anesthesiology at the Chinese University of Hong Kong, was delivered after a nine-strong jury concluded he was guilty of the crime after seven hours of deliberation.

High Court Justice Julianna Barnes Wai-ling said Khaw, who is intelligent and well-educated, had developed a calculated, deliberate plot to murder his wife. 

The estranged husband, who was allegedly having an affair with one of his students, co-owned multiple properties with his wife. Both circumstances could be the motivation of the murder, according to the justice.

The justice also said Khaw should take full responsibility for his daughter’s death, although he had not intended to kill her. 

READ MORE: HK professor charged with murder of wife, daughter

Khaw, a specialist in anesthesiology, was alleged to have put a leaking inflatable yoga ball containing carbon monoxide in the back of a Mini Cooper driven by his wife three years ago.

On May 22, 2015, a jogger found Khaw's wife Wong Siew Fing, 47, and their second daughter Khaw Li Ling, 16, lying unconscious in the car. They were certified dead on arrival at a hospital.

Khaw denied the murder charges after he was arrested on Sept 11 last year. Although admitting to filling the yoga ball with carbon monoxide, Khaw claimed he did it for research purposes and had intended to kill rats at home.

However, Khaw’s Indonesian domestic helper said she had never seen any rats in the house when giving testimony.

Khaw told the court that his second daughter was a suicidal person. But in reviewing the evidence for the jury, the judge said testimonies by witnesses had shown that the girl had an open personality and was bright and cheerful about her future. There was no direct evidence showing she was suicidal, the judge added.

Previously, Khaw’s lawyer claimed that Khaw Li Ling, who feared bugs, may have used the gas as a pesticide without appreciating its deadly nature. But police did not find a plug for the yoga ball in the car, the court heard.

In her instructions to the jury, the judge explained the factors involved in a murder. This included whether the actions of the defendant have led to other people’s deaths or caused severe bodily damage; and whether there is any intent to murder.

bingcun@chinadailyhk.com