The bodies were found by a maid Tuesday afternoon after they failed to check out of their room at the Grand Hyatt Erawan Bangkok, as reported by the Associated Press.
The six were last seen alive when food was delivered to the room Monday afternoon. An employee saw one woman receive the food and surveillance video footage captured the others arriving at the room shortly after. The door was locked from the inside and no one was seen leaving the room, police said.
Staff discovered upon entering the room that the food that had been ordered was left untouched. They located several used teacups on a nearby table situated next to two thermos bottles.
Lt. Gen. Trairong Piwpan, chief of the Thai police forensic division, said authorities found traces of cyanide in the cups and bottles, per the paper.
Autopsies of the six bodies conducted at Bangkok's Chulalongkorn Hospital released on Wednesday found that all six deceased had cyanide in their blood. Kornkiat Vongpaisarnsin, head of the forensic department, said at a news conference that they came to the hypothesis that the deceased had been poisoned, citing the autopsy reports.
Bangkok police chief Lt. Gen. Thiti Sangsawang identified the deceased as three men and three women. Two of them were Vietnamese Americans and four of them were Vietnamese nationals. Their ages ranged from 37 to 56.
Bangkok deputy police chief, Noppasin Punsawat, told reporters that the case appeared to be personal and there was no threat to the safety of tourists.
Police said that the agency obtained information from a relative that a husband and wife, who were among the dead, had invested about 10 million baht ($278,000) with two of the others, which was meant to build a hospital in Japan. The group might have been meeting to settle the matter, a potential motive the police are investigating. Authorities said one person killed the others but did not disclose who was the suspect.
