On 16 February 1988, the eve of Lunar New Year, in Lengkok Bahru, Singapore, 31-year-old Tay Kim Teck (郑金德 Zhèng Jīndé) was attacked by a group of six men.

[1] Tan Ai Soon and Tay Kim Teck were part of a group who was gambling in a market in Lengkok Bahru.

However, after considering the role each attacker had played in the assault, the murder charges against the Tan brothers, Ng and Ong were reduced to rioting.

They found that when Koh first heard about the assault on Tan, he had not completely lost his self-control, as was shown in two instances.

He made three requests to his family; that a temple at River Valley Road handle his funeral arrangements, that he be cremated and his ashes scattered at sea, and that his organs be donated to others.

[6] Before the landmark appeal by Abdul Nasir Amer Hamsah on 20 August 1997, life imprisonment at the time of Koh's offence, conviction and pardon was considered as a fixed jail term of 20 years, with the possibility of one-third reduction of the sentence for good behaviour.

His Buddhist beliefs came from influence by another death row inmate, Lim Joo Yin, who was convicted of drug trafficking.

Lim's accomplice Sim Ah Cheoh, like Koh, had been granted clemency by the President two months earlier in March 1992, with her death sentence commuted to life imprisonment.

[1] As of 2003, Koh had completed his GCE O-Levels and was taking a two-year Institute of Technical Education course in electronics, and should he continue to show good behaviour, he would be released early in September 2005.