The instructor was charged with triple murder following the death of the South Korean family late Wednesday.
 
Yoo was admitted to hospital with apparent stab wounds to his arms and abdomen, telling police he had been attacked in the parking lot of a supermarket. However, police investigated and alleged that Yoo had attacked and killed the boy and his mother at the martial arts studio at the time. 
 
Yoo was denied bail at a five-minute bedside hearing at Sydney's Westmead Hospital, where he was held in police custody. 
 
Police said Yoo knew the mother and child, who regularly took lessons at the taekwondo studio.

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