A day after the killing, Koh's 19-year-old boyfriend Chan Choon Wai (陈俊伟 Chén Jùnweǐ), also Malaysian, was arrested and charged with murder.

Chan, who claimed that he committed the crime out of sudden and grave provocation, was found guilty of murder and sentenced to death a year after killing Koh.

The woman, who was motionless with bruises around her neck at the time of the discovery, was later pronounced dead by ambulance officer Norbayah Md Yasin upon the arrival of the paramedics, while the man, who had slit wounds on both his wrists, was brought to the hospital and later arrested.

The man found lying beside her was her 19-year-old boyfriend, Chan Choon Wai, who was also Malaysian but born in Ipoh and most recently from Kuala Lumpur.

Professor Chao would eventually come to court in January 2000 to testify regarding the victim's cause of death, before he died a month later at the age of 67, making this likely his last major case.

[10][11] Chan, who elected to give his defense, initially told police that on the afternoon of 25 March 1999, he and Koh met up and had sex in their rented room together.

Chan's decision to slit his wrists was just a ploy to give a false impression to the police that there was a suicide pact between him and Koh, rather than him doing so out of guilt for killing his girlfriend.

JC Singh further cited that at the time of the offence, Chan never suffered from diminished responsibility or unsoundness of the mind, as confirmed by the psychiatric evidence provided by the government psychiatrist Dr Stephen Phang.

[26][27][28][29] After his death sentence was upheld through appeal, Chan Choon Wai was hanged in Changi Prison sometime between late 2000 and early 2001 for murdering Koh Mew Chin.

[30] In February 2000, the case of Koh's murder was one of the ten most high-profile acts of violence against women in Singapore that happened during the past year.