A tragic incident at a luxury Bangkok hotel has sparked a high-level investigation in Thailand, potentially threatening the country's tourism industry which aims to attract 35 million visitors this year. According to Reuters, Thai authorities have confirmed that cyanide poisoning caused the deaths of six foreigners, including the suspected perpetrator, whose bodies were discovered in a room at the Grand Hyatt Erawan hotel. Reuters reports that traces of the deadly chemical were found during autopsies and on drinking glasses and a teapot in the hotel room. The victims, all of Vietnamese ethnicity, included two U.S. nationals. Thai police, with assistance…