A Hong Kong court on Wednesday sentenced a Malaysian professor and anesthesiologist to life in prison for killing his wife and daughter using two yoga balls filled with carbon monoxide, a murder the court said was “premeditated and calculated,” the South China Morning Post reports. Khaw Kim Sun, a 53-year-old professor at the Chinese University of Hong Kong, was unanimously found guilty of killing his wife, Wong Siew Fing, 47, and their second child, Lily Khaw Li Ling, 16, in May 2015.