Bangkok police have arrested a 40-year-old Singaporean man at a condominium in Bang Khae after finding methamphetamine, chemicals and alleged orders for highly toxic substances made through the dark web.
Joel Ong Seng Yong was arrested on 3 September and the case was announced the following day. Police said Singapore's Central Narcotics Bureau (CNB) had identified him as a specially monitored criminal with outstanding warrants and a lengthy record involving drugs and serious criminal offences.
Police said the quantity of chemicals, could in theory, kill many people if used in a targeted attack. They also said they found evidence of a discussion of putting poison in a water tank as part of a mass killing plan.
Drugs, cash and chemical materials seized
Police said they found 3 grams of crystal methamphetamine, drug-taking equipment, 200,000 baht in cash and two mobile phones in the condominium, which falls under Lak Song Police Station's jurisdiction.
Investigators also seized half a kilogram of saltpetre, sodium metabisulphite, ammonia solution, nitric acid, borax and two detonator devices. The chemicals have been sent for forensic examination.
According to police, examination of the phones found evidence that Ong had paid 18,000 baht to order toxic substances. Officers alleged he had bought 20 grams of a poison said to be 10,000 times stronger than morphine, as well as 10 grams of drugs used for animal euthanasia or executions.
However, Metropolitan Police deputy commissioner Major General Theeradet Thamsuthee said there was no evidence at this stage of terrorism. Experts had also advised that the chemicals recovered were not sufficient to make a lethal bomb, he said.
Police inquiry began in January
The investigation followed a report to the ONCB's 1386 hotline in late January 2026. The caller alleged that Ong, who had fled criminal cases in Singapore, was hiding in Thailand, using crystal meth and becoming violent.
Police said the report included allegations of assault and unlawful detention with a sexual element. Detectives spent more than three months tracing him, initially facing difficulties because he had entered Thailand posing as a student and was not then listed on Interpol's wanted-person system.
Investigators later went undercover as tourists in central Bangkok and spoke to an entertainer who said she knew Ong. She alleged he had assaulted her so severely that blood vessels in her eyes burst, threatened her with a knife, and suggested they die together.
Overstay and drug charges so far
Ong has initially been charged with possessing and using Category 1 narcotics, methamphetamine and remaining in Thailand after his permission to stay had expired. Further charges relating to explosive preparation and dangerous substances remain under investigation.
Police said Ong told investigators he had previously been imprisoned in Singapore for drug offences for one, three and five years, and received three strokes of the cane. He allegedly fled to Thailand after another offence in 2024, sold assets in Singapore for around 5 million baht and later lost 2.5 million baht to a Singaporean friend.
He claimed the poisons were intended for suicide because he feared a smaller quantity would not work, and said he did not want to be returned to Singapore.
Picture courtesy of ThaiRath
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5 September 2026
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