On 31 December 2001, while volunteering at an end-of-year event, 56-year-old Quek Loo Ming (郭禄明 Guō Lùmíng), a retired laboratory officer, spiked a bottle of water with methomyl and offered it to the chairperson of a resident's committee in Bukit Timah, with hopes that the chairperson, who allegedly mistreated Quek, would suffer from diarrhoea after drinking the contaminated water.

One of the three victims, 62-year-old Fong Oi Lin, died of poisoning on 3 January 2002; the other two – 66-year-old Richard Ho Sin Shong and 38-year-old Wong Ah Kim – were in critical condition before they recovered and survived.

[6] On 31 December 2001, Quek Loo Ming was one of the volunteers at an end-of-year event organized by the resident's committee.

It was alleged that Lum mistreated Quek, treating him like an "errand boy" and never gave him credit for his volunteering work on all occasions.

[3][7][8] According to Quek's testimony to his lawyers and police, he once handled the case of a Filipino maid's death while he was still a laboratory officer at DSS.

In that particular case, the maid had committed suicide by mixing a large dose of methomyl with her coffee before she drank it; methomyl was a strong poison used for pesticides, and could cause death with a large dose while normally affecting the nervous system and cause muscular paralysis.

These three people fell gravely ill and became unconscious after drinking the water and were rushed to the National University Hospital for treatment, where they remained in critical condition.

[11] The remaining two people were 66-year-old retired accountant and vice-president of the resident's committee Richard Ho Sin Shong (何常胜 Hé Chángshèng) and 38-year-old electrician Wong Ah Kim (黄亚金 Huáng Yájīn), who both spent weeks at the hospital recovering from the poison and survived.

[12] The contaminated water was disposed of by Fong prior to her falling ill, because she found it smelly, which prevented other people present at the event from consuming it.

[25] On 11 January 2002, a day after his arrest, Quek was charged with murder for having caused Fong's death by methomyl poisoning.

On 18 January 2002, Quek returned to court to be charged with two counts of voluntarily causing grievous hurt by dangerous means for injuring both Wong and Ho.

The prosecution argued for Quek to be sentenced to the maximum sentence of life imprisonment, or at least a jail term lasting more than ten years in view of the charges, placing their emphasis on the extent of harm caused to the victims and the eventual death of Fong as an consequence of Quek's actions, as well as for the sake of deterrence and appease the outrage of the community's feelings.

Judicial Commissioner Choo stated that while the nature of the offences were deplorable and abhorrent and a life was lost due to a small issue,[40] he noted Quek was a first offender with a "unblemished record" and contributed to society during his time under the government, and also noted Quek was genuinely remorseful of his actions.

[47] Quek's wife also publicly apologized to Fong's bereaved kin, and also to the other two victims and their families for her husband's crime.

[49][50] Seeking a sentence of more than nine years, the prosecution argued that Quek's actions of poisoning the water were not done out of impulse, and it demonstrated a high level of premeditation on his part.

[2][52] They stated that the poisoning of the water was not done by a layman, but by a former laboratory officer who had the knowledge that methomyl was an extremely potent poison that caused the death of a Filipino maid years ago, and the effects of the methomyl were so much so that even a small volume of it had killed 62-year-old Fong Oi Lin and placed both the lives of 38-year-old Wong Ah Kim and 66-year-old Richard Ho in grave danger.

In addition, Anandan stated he respected Quek's wife as a remarkable woman who calmly supported her husband throughout the proceedings.

At the time of writing, Quek's wife planned to leave Singapore and emigrate to another country, and also wanted her husband to join her upon his release.