Bangkok | The chief of the Thai police forensic division said Wednesday that police have found traces of cyanide in the coffees of six people found dead in a central Bangkok luxury hotel.

The bodies were found Tuesday in Grand Hyatt Erawan Hotel in downtown Bangkok. Upon checking hotel records, there were no other visitors to the room apart from the six that were found, police said. They had last been seen alive when food was delivered to the room on Monday afternoon.

Lt. Gen. Trairong Piwpan, chief of the Thai police force's forensic division, said that traces of cyanide were found in the empty cups found in the room by police, but initial results of an autopsy are expected Thursday.

Bangkok police chief Lt. Gen. Thiti Sangsawang identified the dead as two Vietnamese Americans and four Vietnamese nationals, and said there were three males and three females.

The suspected motive for the deadly act may have been about money invested with one by a husband and wife, who felt it was not being properly used, said Noppasin Punsawat, Bangkok deputy police chief, citing information obtained from relatives of the victims.

The Vietnamese and United States Embassies have been contacted over the deaths, and the American FBI is involved in the investigation, said Noppasin.

“This case appears to be personal and will not impact the safety of tourists, ” he said.

Trairong said a mass suicide was unlikely because some of the victims had arranged many things for their trip, such as guides and drivers. He added that the bodies were not grouped in the same place — some were in the bedroom, some in the living room — suggesting that they did not knowingly consume poison and wait for their death together.