A Hong Kong professor sentenced to life over gassing his wife and daughter to death in 2015 has won his appeal at the city’s top court, with the judges ordering a retrial of the murder case.

Court of Final Appeal
Court of Final Appeal. Photo: Kyle Lam/HKFP.

Khaw Kim-sun, a former associate professor at the Chinese University of Hong Kong (CUHK) and an anaesthesiologist, was convicted at the High Court in 2018 of murdering his wife and 16-year-old daughter. The couple got married in 1992 and raised four children.

The high-profile case sparked public attention eight years ago, with details suggesting that a carbon monoxide-filled inflatable exercise ball leaked in a car and killed Khaw’s wife and daughter.

The pair were found dead in their car- a yellow Mini Cooper – on May 22, 2015. Autopsy results showed that they died from inhaling a high concentration of carbon monoxide, but police could not confirm the source of the gas. An exercise ball without a plug was found by police in the boot of the car.

Prosecutors accused Khaw, now 59, of leaving the ball in the car.

high court
The High Court. File photo: Kyle Lam/HKFP.

But Khaw testified during the trial in 2018 that he filled the ball with carbon monoxide at a laboratory in CUHK and brought it home to kill mice in their village house, which he said had a rodent infestation.

A nine-member jury handed down a verdict of 9-0, finding Khaw guilty of two charges of murder. Judge Judianna Barnes said before sentencing that it was shocking to see someone as intelligent and successful as the defendant plan such a murder.

The judge said Khaw not only had an extramarital affair but also jointly owned multiple assets with his wife. Those factors, Barnes added, were motives for the murder of his wife.

The burden of proof

Delivering the ruling at the Court of Final Appeal on Tuesday morning, the five judges at the Court of Final Appeal said Khaw’s conviction should be withdrawn. The appellant argued that the police did not find the plug of the exercise ball during the initial investigation, questioning whether the judge in the initial trial had misled the jury based on this.

Judiciary Court of Final Appeal
The Court of Final Appeal in Hong Kong. Photo: GovHK.

In addition, the appellant also argued that the judge misled the jury into thinking that the defendant had a burden to prove his innocence, which is not in line with court procedure.

In Hong Kong courts, the burden of proof is generally on the prosecution at trials of criminal cases, which has to convince the court that the defendant is guilty of the offence beyond reasonable doubt.

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Irene Chan is a reporter at Hong Kong Free Press and has an interest in covering political and social change. She previously worked at Initium Media as chief editor for Hong Kong news and was a community organiser at the Society for Community Organisation serving the underprivileged. She has a bachelor’s degree in Journalism from Fudan University and a master’s degree in social work from the Chinese University of Hong Kong.

Irene is the recipient of two Society of Publishers in Asia (SOPA) awards and three honourable mentions for her investigative, feature and video reporting. She also received a Human Rights Press Award for multimedia reporting and an honourable mention for feature writing.