A 56-year-old woman was believed to have poisoned five other Vietnamese tourists with cyanide served in cups before drinking the poison herself in a luxury hotel in Bangkok, police said on Wednesday. The bodies of three men and three women had been discovered on Tuesday evening by staff in a suite of the Grand Hyatt Erawan Hotel in Bangkok’s city centre. A first inspection of the scene revealed no traces of violence and robbery was quickly ruled out. On Wednesday, police said in a press conference they believed one of the six tourists, two of whom also held US passports, was behind the deaths….