A professor accused of murdering his wife and daughter with a gas-filled yoga ball sobbed uncontrollably when he called his eldest daughter to tell her the pair had died, a Hong Kong court heard on Monday. During a day of emotional testimony, Khaw May Ling said the sudden call made her think Khaw Kim Sun was joking when he telephoned her at university in Malaysia , until he sent her pictures of what had happened, the High Court heard. Khaw Kim Sun, 53, an associate professor in anaesthesiology at Chinese University, is standing trial over the deaths of his wife Wong Siew Fing, 47, and 16-year-old daughter Lily Khaw Li Ling, who died of carbon monoxide poisoning in their car on May 22, 2015. The Malaysian national has pleaded not guilty to two counts of murder. On Monday, Khaw May Ling, told the court how her father called her in Malaysia, where she was studying, to give her the news. “I thought he was playing a joke or something,” she said, while fighting back tears. Someone else then picked up the phone to explain what was going on, Khaw May Ling told the court. Her father then sent her pictures, and at the point she “kind of realised he wasn’t joking any more”. She returned to Hong Kong the next day to find her father, whom she described as normally being strong, an emotional wreck. Residents evacuated from Hong Kong housing block after electricity meter fire Khaw May Ling also told a Hong Kong court how betrayed she felt when she first discovered he was having an affair with her former tutor, and described the high expectations her father placed on his children. Her testimony prompted Khaw Kim Sun, who also works at Prince of Wales Hospital in Sha Tin, to smile one moment and shed tears the next. “At first, I felt slightly betrayed he would do that,” said Khaw May Ling, during cross-examination by defence counsel Gerard McCoy SC. I felt that I could understand why my father would want to look for someone else Khaw May Ling She said the lover, Shara Lee, first came to the house to teach her and her late younger sister Lily Chinese in 2004 and 2005. Prosecutors, who sought to link the murder and the affair, have also said Lee was one of Khaw Kim Sun’s students. The daughter said she began to suspect her father and Lee were having an affair around 2012, while her mother found out in 2013 or 2014, she said. But, as betrayed as she felt, Khaw May Ling said she later came to understand her father’s actions, just as her mother, who, though initially upset, came to accept it about a year before her death. “My parents hadn’t been getting on for a while. I felt that I could understand why my father would want to look for someone else,” she said, even though she still felt bad for her mother. Khaw May Ling said her parents did all they could to remain civil for the benefit of the children, with her father taking the entire family to Australia for a skiing trip, after which they came back more relaxed. She called Lily Khaw Li Ling “a free spirit” who, while impulsive at times, was her soulmate and a very caring person, who took a keen interest in humanities subjects at her Renaissance College in Ma On Shan. Sitting in the dock, her father occasionally smiled as his eldest daughter recalled the fun times she used to have with her younger sibling, but he was reduced to tears when he heard about the immense pressure he placed upon them. Prosecutors have said they believe that, in a “deliberate and calculated” plot, Khaw Kim Sun ordered carbon monoxide through his university office, claiming it was for research purposes. Instead, he filled the yoga ball with the toxic gas before unplugging it and leaving it inside his wife’s Mini Cooper. It was later discovered inside the car, deflated, alongside the bodies of Wong, and Lily Khaw Li Ling, at the Sai O Village bus stop in Ma On Shan. After his arrest, Khaw told police his teenage daughter might have committed suicide under stress, the court heard previously. On Monday, the eldest daughter, who is now doing her medical science degree in Malaysia, said both she and her late sister had been diagnosed with attention deficit hyperactivity disorder, while Lily Khaw Li Ling was also dyslexic. She said her father had not been very understanding and when she was prescribed with antidepressants at the start of 2015, Khaw Kim Sun had trivialised her condition and told her not to take them. Khaw May Ling added that her departure for Malaysia to study left her concerned that her father’s attention would turn to Lily Khaw Li Ling. “He was concerned that Lily was not trying hard enough in her studies,” she said. McCoy quizzed Khaw May Ling as to whether she feared “the darkest thing” would happen to her sister, to which she replied that she tried to stay away from those thoughts. Marriage scam ringleaders who lured young into US$730,000 scheme found guilty However, geography teacher Trevor Newman, who taught Lily Khaw Li Ling, painted the popular teenager in a positive light, and testified that she never caused any concerns in school. After his arrest, Khaw Kim Sun had also told policehe brought home some carbon monoxide from his university because he wanted to eradicate a rat problem at hishome in Tai Tung village, Ma On Shan. Prosecutors have argued that there had never been a rat problem. On Monday, Khaw May Ling testified that there were rats in the house, to the extent the family would put out traps in an attempt to catch them, alongside other pests such as skunks and cockroaches. She also said Lily Khaw Li Ling was afraid of those particular animals. The trial continues before Mrs Justice Judianna Barnes Wai-ling on Tuesday.