On 31 October 1983, a 66-year-old woman named Chong Kin Meng (钟剑明 Zhōng Jiànmíng) was found murdered inside her Clementi flat by her foster son's wife.

The 23-year-old suspect, Teo Boon Ann (张文安 Zhāng Wénān), was found to have entered the flat under the pretense of providing Chong's foster son a wedding invitation card and a gift in his father's name, before he proceeded to kill her during a robbery attempt.

[1] On the evening of 31 October 1983, 25-year-old Ong Chin Choo (王珍珠 Wáng Zhēnzhū), a factory worker, returned home from work when she discovered the dead body of her 66-year-old foster mother-in-law Chong Kin Meng inside the living room, with extensive injuries and bruises on her neck, head and arms.

In his trance, Teo even drew a layout of the living room where Chong was killed, and told Woo that a phone call would come in seven days to reveal the identity of the killer.

He testified that on the day itself, he wanted to go rob the old woman, and entered her home under the pretense of passing to Chong a wedding invitation card for her foster son and some cakes.

Teo, who said he was full of panic and fear at that time, quickly left the flat after snatching the five-dollar note that laid next to the telephone.

Professor Chao explained that the fractures and bruises on the neck could only be caused by strangulation with great force for a prolonged period of time, the rib fractures were due to someone sitting on top of her during the strangulation, and the head injuries were a result of Teo intentionally using the stool to violently hit at her head multiple times and with great force.

Although Tan did not agree to join Teo in the killing, she had recorded that particular telephone conversation inside her diary and showed it to the court.

He also stated that there was utter brutality displayed by Teo during the "cruel and deliberate" attack he unleashed upon the elderly woman, who suffered extensive injuries.

As such, Ho argued in summary that the case of Chong's death was one of premeditated murder and urged the court to reject Teo's defences and convict him as charged.

[26] On 3 February 1987, the trial judges - Justice Punch Coomaraswamy and Judicial Commissioner Chan Sek Keong - issued their written verdict.

They were of the opinion that Teo had raised the wooden stool to hit Chong on the head repeatedly with violence and considerable force.

[30][31] On 20 April 1990, 30-year-old Teo Boon Ann was put to death at Changi Prison for killing 66-year-old Chong Kin Meng.