Hong Kong yoga ball murder: what has changed since the verdict in 2018?

Former university professor and anaesthesiologist Khaw Kim Sun received a life sentence after a Hong Kong jury found in a retrial that he was guilty of murdering his wife and daughter with an inflatable yoga ball filled with carbon monoxide.

The pair was found dead in a Mini Cooper parked on the side of the road in Sai Kung, mere minutes in driving distance away from their home on May 22, 2015.

The Post explores how the defence and the prosecution changed strategies, including the latter’s omission of the discovery of the ball’s stopper in Khaw’s drawer, the piece of evidence that led to the Court of Final Appeal’s ruling in 2023 to quash the conviction and order a retrial.

1. Prosecution case

Both prosecutors – Senior Counsel Andrew Bruce in 2018 and Jonathan Man Tak-ho in the retrial – put an emphasis on Khaw’s excuse of storing carbon monoxide. Khaw said he needed it for a research project on using oxygen to resuscitate rabbits poisoned with carbon monoxide. But prosecutors said the research had little to no clinical value and was an excuse for the professor to obtain the lethal gas for other purposes.

In both trials, none of the prosecution witnesses said they had seen Khaw putting the yoga ball in the boot of his wife’s Mini Cooper and pulled the stopper to release the gas. But Bruce had asked the jury to look at circumstantial evidence.

Prosecutors in the two trials argued Khaw was the only person in the family who had a motive to kill his wife Wong Siew Fing, 47, while mistakenly taking the life of his 16-year-old daughter Khaw Li Ling.

Prosecution in the 2018 trial relied on a piece of evidence to link Khaw with the yoga ball found in the car: a stopper. While investigating, police discovered half a year after the incident that the stopper of the yoga ball in the boot was missing, they found a stopper – uncertain whether it was the same or different one – in Khaw’s drawer at home.