A Malaysian professor accused of murdering his wife and daughter with a gas-filled yoga ball in Hong Kong was tied up in a meeting with more than 250 students on the day the pair were found dead, his lawyer said at his murder trial on Tuesday.
Khaw Kim Sun had been attending a university event at 1.30pm on May 22, 2015, just two hours before a passer-by found his wife, Wong Siew Fing, 47, and daughter, Lily Khaw Li Ling, 16, unresponsive in their car on a roadside, defence counsel Gerard McCoy SC told the High Court.
The barrister did not say how long the function had lasted, but the court previously learned from a recorded interview Khaw did with police that it was a three-hour student assessment session.
During the event, 255 third-year medical students presented projects, the barrister said, citing an email Khaw, a specialist in anaesthesiology, and his colleagues had circulated.
The evidence was presented as McCoy cross-examined Gavin Joynt, Khaw’s supervisor at the Chinese University of Hong Kong. The chairman of the department of anaesthesia and intensive care was called as a prosecution witness.
But Joynt said he was unsure whether Khaw was present at the session that day, as he had not attended the event himself.
Khaw, a doctor at Prince of Wales Hospital in Sha Tin, also carried out surgery on May 22, McCoy said.
However, Joynt could not confirm that claim because the university did not have a logging system, the witness said.
“I guess if you need that information we can try to provide it,” Joynt told the court.
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Khaw, 53, has denied two counts of murder. Prosecutors allege he left a yoga ball leaking carbon monoxide in the family’s yellow Mini Cooper, causing his wife and daughter to die of gas poisoning.
Government chemist Wong Koon-hung earlier estimated it would have taken 15 minutes for the carbon monoxide to reach a level 35 times the 200 parts per million at which the gas is deemed dangerous. The level would have remained so for 155 minutes, he testified.
Prosecutors have also put other experts on the stand to comment on why Khaw set up an experiment just days before the deaths that required use of the toxic gas.
Joynt on Tuesday echoed the opinion of Kwong Yok-lam, a leading haematologist at the University of Hong Kong, who testified on Monday that the experiment had no clinical use.
Joynt said Khaw’s experiment involved ascertaining how oxygen of 60 per cent concentration could help improve the situation of a rabbit exposed to carbon monoxide. But it was already well established that 100 per cent oxygen would be used in real life to treat patients suffering from carbon monoxide poisoning, Joynt said.
But challenging that position, McCoy cited a prominent medical journal which stated that too much oxygen could increase patient mortality.
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“Are you ... able to contemplate that, actually, providing 100 per cent oxygen in carbon monoxide toxicity cases may itself not be the safest way?” McCoy asked the intensive care specialist.
Joynt said there might be another way in the future, but pure oxygen presently remained the most suitable therapy.
He said the journal only reminded doctors they should be watchful when using oxygen in situations other than carbon monoxide poisoning.
McCoy noted that one of Khaw’s previous pieces of research had been adopted by medical professionals overseas. The study involved an assessment of how extra oxygen supply could affect a mother undergoing a caesarean section. Joynt did not dispute this.
The jury in the trial were on Tuesday taken to view the Mini Cooper at Hong Kong’s Police Training School in Wong Chuk Hang.
The trial will continue on Wednesday before Mrs Justice Judianna Barnes Wai-ling.