Examining the body - identified as that of a 32-year-old Russian from the Siberian city of Yakutsk - Pol Lt Col Teerasak Boonsang and forensics officers found the victim had deep gashes on both arms and seven stab wounds in the chest.
Police concluded that he committed suicide.
Friends of the victim said he checked into the hotel on July 19 and was due to check out today to fly back to Russia.
“We gathered in front of the hotel this morning to take the shuttle bus and when he didn’t show up, we asked hotel staff to check his room,” one said.
A member of the hotel staff said, “The last time we saw him was at breakfast on Monday (August 11) and there has been a ‘Do not disturb’ sign on the door since yesterday.”
Police are still collecting evidence, and have been in touch with the Russian Embassy to discuss the case. The dead man is not being named until there has been a chance for his family to be informed.