Between November 1992 and September 1993, at two locations within Singapore, a group of Thai migrant workers committed armed robberies at two construction sites located in Lim Chu Kang and Tampines respectively, which resulted in the deaths of three foreign construction workers, one Myanmar citizen in November 1992 and two Indian citizens in September 1993.
[10] The investigation of the list of possible suspects were eventually narrowed down to the theory that a Thai gang was allegedly responsible for these cases, and there were evidence that the stolen survey equipment were being sold in Thailand (most of them) and other neighbouring countries.
[12][13] By July 1994, the police managed to arrest four of the seven suspects (all of whom were Thai illegal immigrants) who were allegedly responsible for the murders of Vallaisamy and Chokalingam back in September 1993.
However, after the prosecution appealed, Manit's charges of gang robbery with murder were restored and he was brought back to court to give his defence.
[15][16] Out of the four, Panya Marmontree and Prawit Yaowabutr were actually arrested for an unrelated case of committing burglary at a construction site in February 1994, before they were subsequently linked to the murders of Chokalingam and Vallaisamy and charged for the present offence.
In his judgement, Justice Sinnathuray found that the prosecution had proven their case against the trio beyond a reasonable doubt, and having noted that the crime was committed in an extremely brutal and violent manner, and cited that there were an increasing trend of murders happening at construction sites throughout the past three years or so, Justice Sinnathuray believed that the maximum punishment should be imposed to show the abhorrence and condemnation of the court and public for such crimes.
Therefore, the three men - Manit Wangjaisuk, Panya Amphawa, and Prasong Bunsom - were found guilty of murdering Thaung during the course of gang robbery, and sentenced to death.
On 8 March 1996, a week before the five men were due to hang, the Thai government's appeal for clemency was rejected by then President of Singapore Ong Teng Cheong.
[32] Amnesty International, an international human rights group, condemned the Singaporean government for executing the five Thai workers despite the clemency plea from Thailand, and they stated that the death penalty was an "ultimate cruel, inhuman and degrading punishment", and would continue to push for Singapore to abolish the death penalty altogether.
Many Thai politicians also acknowledged that they had done their best to seek clemency for the five men, and they urged their citizens to abide by the laws of whichever country they live, study and work in.
[39] The executions of the five Thai construction site murderers were briefly mentioned in a real-life crime book titled Talking with Serial Killers: A Chilling Study of the World's Most Evil People, written by criminologist Christopher Berry-Dee and first published in 2023.
The executions were mentioned in the chapter covering John Martin Scripps, a British spree killer who was executed for murdering a South African tourist in a hotel in Singapore, and their cases were mentioned to show the impartiality of the judicial system in Singapore, which emphasized that regardless of a criminal's nationality, he or she would be subjected to equal and fair punishment under the law.
[40] In January 2015, the 1995 appeal case of the four men - Panya Marmontree, Prawit Yaowabutr, Manit Wangjaisuk, and Panya Amphawa - against their convictions for killing Chokalingam Arumugam and Vallaisamy Aryian was referenced to by the Court of Appeal in a landmark ruling of a murder case that coined the sentencing guidelines for unpremeditated murder in Singapore.