A martial arts instructor who murdered a couple and their young son in a fit of jealousy will spend the rest of his life behind bars, a New South Wales court has ruled.
A horrific sequence of violence
Kwang Kyung Yoo, a 51-year-old taekwondo teacher, was sentenced to life imprisonment without parole in the NSW Supreme Court on Tuesday. The court heard how, in February 2024, Yoo strangled a 41-year-old mother at his studio in North Parramatta, in western Sydney, before teaching a class. He then returned to strangle her seven-year-old son.
After taking the woman's Apple Watch, Yoo drove her BMW to the family's home in Baulkham Hills. There, he fatally stabbed the 39-year-old father. The victims, who cannot be named due to legal restrictions protecting child victims of crime, were known to Yoo.
Jealousy and a web of lies
Justice Ian Harrison found the three murders were "objectively very serious" and motivated by Yoo's jealousy. Financially struggling, Yoo had become envious of the family's apparent success. "These killings were horrific and violent acts, senselessly cruel and cynical, perpetrated without a trace of human compassion," Justice Harrison told the court.
The sentencing hearing in November revealed Yoo had constructed an elaborate fantasy life to impress others. He falsely claimed to have met mining magnate Gina Rinehart, qualified for the 2000 Olympics, owned a Lamborghini, and lived in Sydney's affluent eastern suburbs. He even sent emails to himself pretending to be important people.
Justice Harrison noted Yoo told a psychologist the lies grew "bigger and bigger" as his wife and students asked more questions. Despite this, he never achieved the success he craved, a burden compounded by unrealistic childhood expectations from his parents and culture.
A final reckoning in court
As the life sentence was handed down, Yoo, formerly known as 'Master Lion', sat with his head bowed. He did not look at the victims' grieving family and supporters, who sobbed in the public gallery. Friends of the family later told reporters they were satisfied with the outcome.
Justice Harrison stated that murdering the young boy was an "egregious breach of trust," as both he and his mother had been lulled into a false sense of security. Although Yoo had planned the crimes and surveilled the family home, he made no attempt to hide from CCTV in his studio or conceal the bodies.
At the time of his arrest, Yoo was tens of thousands of dollars in debt and behind on his rent. During the proceedings, he was handed a box of tissues as the judge described his expressed remorse. In a letter to the court, Yoo wrote that he was "held captive by sin" and wished he could turn back time. "I pray every day for the people I have hurt," he said.
Justice Harrison set no parole date, meaning Kwang Kyung Yoo will die in prison. The judge said the sentence sent a clear message that murdering people "for effectively no reason at all" would not be tolerated by the community.
