Thai authorities reported Wednesday that traces of cyanide were discovered in the cups of six Vietnamese and American guests at a prominent luxury hotel in central Bangkok.
Authorities suspect one of the guests poisoned the others following a dispute over a failed investment.
The bodies were discovered Tuesday at the Grand Hyatt Erawan Bangkok, located at a bustling intersection in the capital surrounded by malls, government buildings and public transit.
The guests were last seen alive Monday afternoon when food was delivered to their room. Staff observed one woman receiving the delivery, and security footage confirmed the others arriving shortly after.
There were no additional visitors, no signs of anyone leaving the room, and the door was locked. The discovery was made Tuesday afternoon by a maid after the guests failed to check out.
Lt. Gen. Trairong Piwpan, chief of the Thai police force's forensic division, said traces of cyanide were found in the cups and thermoses recovered from the room. Initial autopsy results were expected later Wednesday.
Bangkok police chief Lt. Gen. Thiti Sangsawang identified the deceased as two Vietnamese Americans and four Vietnamese nationals – three men and three women. Their ages ranged from 37 to 56, according to Noppasin Punsawat, Bangkok deputy police chief. He said the case appeared to be personal and would not affect tourist safety.
Noppasin said a husband and wife among the victims had invested money with two others, suggesting financial motives. The investment was intended for a hospital in Japan, and the group may have been meeting to resolve the matter.
Bangkok police chief Lt. Gen. Thiti Sangsawang said Tuesday that four bodies were found in the living room and two in the bedroom. He noted that two victims appeared to have attempted to reach the door but collapsed before doing so.
Noppasin stated Wednesday that a seventh person listed on the hotel booking, a sibling of one victim, left Thailand on July 10 and is not believed to be involved in the deaths.
The Vietnamese and United States embassies have been notified, and the American FBI was en route, Prime Minister Srettha Thavisin said.
He added that the case was unlikely to affect a conference with Russian Energy Minister Sergei Tsivilev at the hotel later Wednesday. "This wasn’t an act of terrorism or a breach in security. Everything is fine," he said.
Trairong dismissed the possibility of mass suicide, citing plans made by some victims for future activities like tours and transportation. He also pointed out that the victims being found in different parts of the hotel room suggested they did not knowingly consume poison together.
U.S. State Department spokesperson Matthew Miller in Washington expressed condolences to the victims' families. He said the U.S. was closely monitoring the situation and would liaise with local authorities.
U.S. Secretary of State Antony Blinken spoke with his Thai counterpart on Tuesday, though it's unclear if the deaths were discussed during their conversation.
In 2023, Thailand was shaken by reports of a serial killer who used cyanide to poison 15 people over several years. Sararat Rangsiwuthaporn, known as "Am Cyanide," murdered at least 14 individuals to whom she owed money, becoming the country's first female serial killer. One person survived.