The amount of carbon monoxide in a deadly yoga ball could have been at least 35 times the dangerous level, a forensic scientist told the murder trial of a Malaysian professor on Friday.
Government chemist Wong Koon-hung ran simulations of the leak, and told the High Court that at one point during his experiment the concentration of carbon monoxide in the car went beyond 7,000 parts per million (ppm). He said any reading of more than 200 ppm would be dangerous.
Khaw Kim Sun, 53, is accused of placing the ball, leaking the noxious gas, in the boot of the car which his wife Wong Siew Fing, 47, and daughter Lily Khaw Li Ling, 16, were in on May 22, 2015.
On Friday, Wong said he conducted a series of tests in 2015 and 2016 on the same grey yoga ball and yellow Mini Cooper Khaw was accused of using. He said he found no trace of the potentially deadly gas inside the ball, before the simulations.
Wong said the experiments, and the amount of the gas released, required a heavy-duty carbon monoxide detector, as a normal monitor can trace no more than 1,000 ppm of the gas.
“It’s extremely rare we come across this kind of concentration,” he said.
In three of the experiments, he set up simulations in accordance with the allegations against Khaw. He placed a yoga ball containing carbon monoxide into the Mini Cooper’s boot, before removing its plug and closing the car doors.
One experiment, which lasted five hours, picked up a reading of more than 7,000 ppm of carbon monoxide inside the car after the gas had leaked for about 15 minutes.
Wong could only say it was more than 7,000 ppm, because the amount in the air after 155 minutes was beyond what the monitor could measure.
Wong also recounted how the yoga ball, 58cm in diameter, deflated slowly, in a way that he likened to a souffle, rather than a balloon.
It’s extremely rare we come across this kind of concentration
Wong Koon-hung, government chemist
He noted that when he placed the ball inside the vehicle it could only be inflated to about three-quarters of its full size or it would not fit.
Prosecutors have said they believed Khaw, who was having an affair with his student, Shara Lee, at the time, had orchestrated a “deliberate and calculated” plot in ordering carbon monoxide through his university office and claiming it was for research purposes.
He ended up, they said, using it to murder Wong and their daughter, whose bodies were found inside the car, at the Sai O Village bus stop in Ma On Shan.
In mitigation, defence counsel Gerard McCoy SC challenged Wong that some of his methods had no “scientific validity” to which Wong disagreed.
Khaw has claimed his daughter used the yoga ball to commit suicide.
The trial continues before Mrs Justice Judianna Barnes Wai-ling on Monday.
This article Carbon monoxide in car during Hong Kong yoga ball killing ‘35 times dangerous level’ first appeared on South China Morning Post