Local police suspect that the killer was among those who died, all of whom were Vietnamese.
Authorities in Thailand are investigating the deaths of six Vietnamese people, two of whom have U.S. citizenship, at a luxury hotel in Bangkok, likely caused by cyanide poisoning.
The six—three women and three men—were found dead in a room at the Grand Hyatt Erawan hotel by a staff member on July 16. Local police stated that there were no signs of physical violence.
Bangkok police chief Lt. Gen. Thiti Sangsawang said the victims checked into separate rooms upon their arrival over the weekend. He noted that police were still searching for a seventh person connected to the victims.
“The property as far as we can see has not been ransacked,” Lt. Gen. Sangsawang told reporters.
He said police believe that the victims did not harm themselves and suspect that the killer was among the dead.
Local officials said traces of cyanide were detected on drinking glasses and a teapot in the room where the bodies were found.
The bodies were sent to Chulalongkorn Hospital for autopsies, and traces of cyanide were detected.
“We can assume that the six died from cyanide,” Chulalongkorn Hospital official Kornkiat Vongpaisarnsin told reporters. Authorities were still investigating how the cyanide was obtained.
Thai Prime Minister Srettha Thavisin has urged authorities to investigate the “mysterious deaths” and said that the incident will not affect the country’s tourism, according to a Thai government statement.
U.S. officials are closely monitoring the case and are prepared to provide consular assistance to the families of the two Vietnamese American victims, State Department spokesman Matthew Miller told reporters.
“We offer our sincere condolences to the families on their loss,” he said.
Mr. Miller said local authorities were responsible for the investigation.
“We do reach out to local authorities often to communicate with them when it involves the death of a U.S. citizen, and we will certainly be doing so here,” he said.
Vietnamese Foreign Ministry spokesperson Pham Thu Hang confirmed that four of the victims were Vietnamese citizens and that Vietnamese authorities are in the process of verifying their identities.
“We would like to express our deepest condolences to the families of the victims and hope that they will soon overcome this great loss,” the spokesperson said in a statement.
The spokesperson said the Vietnamese Embassy in Thailand will closely coordinate with local authorities to determine the cause of the deaths.
Reuters contributed to this report.