Dr. Khaw, 53, an associate professor in anesthesia and intensive care at the Chinese University of Hong Kong, had designed an experiment to test the effect of carbon monoxide on rabbits. A student with whom Dr. Khaw had begun an extramarital relationship had also been involved in the experiment. He was later seen filling two yoga balls with the gas. 
 
 When Dr. Khaw, who is Malaysian, was questioned by officers, he told them that he had transported the carbon monoxide in a yoga ball from the university to kill rats at his home. He said that his daughter Lily had seen him leave the ball in the family’s exercise area, and that, after his warnings about its lethal contents, she may have used it to commit suicide. 
 
 Dr. Khaw’s defense lawyer, Gerard McCoy, tried to build a case by portraying Dr. Khaw as a loving father who had inadvertently driven his daughter to kill herself because of his high expectations for her academic achievement. He argued that Dr. Khaw had found it difficult to empathize with his children’s learning disabilities and mental health issues. 
 
 Later, in his closing remarks, Mr. McCoy said that Lily could have tried to use the gas-filled ball to kill insects without anticipating its fatal consequences. 
 
 The prosecutor, Andrew Bruce, described the deaths as a “deliberate and calculated murder.” 
 
 There was also the question of motive. For a few years before her death, Ms. Wong had known about her husband’s affair with the woman who had once tutored their children. In interviews with the police, Dr. Khaw said that he had stayed married to his wife because neither of them could “cope with four children individually.” Ms. Wong had told her yoga teacher that they did not divorce because her husband did not want to divide their assets. ||||| Image copyright Getty Images Image caption A yoga ball was found in the boot of a locked car in which Mr Khaw's wife and daughter were found dead 
 
 An anaesthetist killed his wife and 16-year-old daughter using a yoga ball filled with carbon monoxide, a Hong Kong court has heard. 
 
 Prosecutors said Khaw Kim-sun left the inflatable ball in the boot of a car where the gas leaked out and killed them. 
 
 The pair were found dead inside a locked car in 2015, in a case that initially baffled police. 
 
 Mr Khaw has pleaded not guilty to two counts of murder. 
 
 A post-mortem examination showed his wife and eldest daughter had died from carbon monoxide poisoning. Police found a deflated yoga ball in the back of the yellow Mini Cooper in which their bodies were discovered. 
 
 Prosecutors told Hong Kong's High Court that Mr Khaw had deliberately plotted to kill his wife because he was having an affair and she would not grant him a divorce, the South China Morning Post said. 
 
 But they said it was unlikely he wanted to kill his daughter. He allegedly told his younger daughter to stay at home to complete homework. 
 
 Eyewitnesses said they saw Mr Khaw, an associate professor at Hong Kong's Chinese University, filling two balls with carbon monoxide, reports said. 
 
 He told colleagues he was going to kill rabbits with the gas, but reports say he contradicted himself by telling police he wanted to use it to get rid of rats at his home. 
 
 The trial continues.
– Three years after anesthesiology professor Dr. Khaw Kim-sun's wife and 16-year-old daughter were found unresponsive in a Mini Cooper in Hong Kong, Khaw has been convicted of their murders and was on Wednesday sentenced to life in prison. The case received international attention due to its bizarre mechanics: The women succumbed to carbon monoxide poisoning, and a deflated yoga ball—one believed to have held the gas—found in the trunk was pinpointed as the murder weapon. The New York Times reports Khaw's lawyer argued that his daughter, Lily Li-ling Khaw, used the ball to commit suicide. It reports Gerard McCoy claimed the intense pressure Khaw, 53, put on her to succeed academically led the teen to use the ball, whose lethal nature she had been warned about, to take her life. The South China Morning Post reports McCoy offered a different possible explanation in his closing remarks, saying it was possible she used it to kill bugs, which frightened her, without understanding just how potent the gas was.