The daughter of an anaesthetist accused of gassing his wife and another daughter to death using a yoga ball filled with carbon monoxide described her dead sister as her "soulmate" in a Hong Kong court Monday.
Prosecutors have accused Khaw Kim-sun of leaving the inflatable ball in the boot of a car where the gas leaked out and killed his wife and 16-year-old daughter Lily.
Khaw, 53, was having an affair and his wife would not grant him a divorce, prosecutors said.
They accused him of hatching a deliberate plot to murder her, but said it was likely he had not intended to kill his daughter.
Khaw's eldest daughter May-ling, 19, spoke of her sister at the High Court trial Monday.
"Lily was two-and-half years younger than me. She was probably my soulmate. We were very close and we had a lot in common," she told the court.
She described her sister as brave and a "free spirit" but also said she was impulsive and quick to anger, without giving further details.
May-ling said she was aware of her father's affair with Shara Lee, who was her Chinese tutor and also taught Lily.
"At first I felt slightly betrayed but at the same time my parents hadn't been getting along well. I could understand my father would find someone and I felt bad for my mum," she told the court.
Khaw's wife Wong Siew-fung and Lily were found on a roadside in a locked yellow Mini Cooper in 2015, in a case which initially baffled police.
The pair were certified dead at the same hospital where Khaw worked and a post-mortem concluded they had died from inhaling carbon monoxide.
Police found a deflated yoga ball in the back of the car.
A professor from the Chinese University of Hong Kong, where Khaw was based, told the court Monday that he had seen the anaesthetist fill two yoga balls with carbon monoxide, saying he was taking them to the chemistry department for tests.
The court heard earlier in the trial that Khaw had told colleagues he planned to use the gas on rabbits, but later told police that he had taken it to get rid of rats at home.
Asked by the defence whether there were animals in the family home in Sai Kung, a largely rural area in the north of Hong Kong, May-ling said there had been mosquitoes, cockroaches and rats.
The case continues later Wednesday.