The group of three men and three women had checked into the hotel at separate times after arriving on Saturday and Sunday, according to the chief of Bangkok’s Metropolitan Police, Thiti Saengsawang.
They booked different rooms – four on the seventh floor and one on the fifth floor.
Cleaning staff discovered the six bodies on Tuesday afternoon – all in the fifth-floor room – after the guests failed to check out as scheduled.
There were no signs of robbery or a struggle. The room was locked from the inside.
Plates of uneaten food ordered from room service were left on a table. Some were still covered in plastic wrap.
Thai police said late on Tuesday that they suspected a case of poisoning as “suspicious substances” were found on the bottom of several glasses in the room.
Authorities were looking for a seventh guest, a Vietnamese national.
