Wasn't there a couple found dead in a hotel in Phi Phi last year under similar circumstances?
It seems there was a 2009 case like that:
http://www.stuff.co.nz/world/asia/7118010/Canadian-sisters-found-dead-in-Thailand
The deaths of two Canadian sisters in Thailand has similarities to the 2011 death of a New Zealander in the same country.
Thai media has reported that the sisters were found dead in their Phi Phi Palm Residence Hotel room in a southern resort island of Phi Phi.
The Manager newspaper website quoted police Lieutenant Colonel Rat Somboon as saying the women had probably been dead more than 12 hours when their bodies were discovered Friday with vomit and other signs of a toxic reaction.
Canadian Foreign Affairs spokesman John Babcock confirmed that two Canadian citizens died in Thailand but did not provide further details. He said Canadian consular officials in Bangkok are providing assistance to the family and are in contact with local authorities.
In February, 2011, New Zealander Sarah Carter died and her friends Emma Langlands and Amanda Eliason became gravelly ill while on holiday in Chiang Mai, northern Thailand.
Thai authorities later ruled that Carter was exposed to chemicals similar to those found in pesticides before she died, but say her precise cause of death cannot be confirmed.
Carter was one of three tourists to die in seeminly mysterious circumstances between January 9 and February 4 in Chiang Mai - the others were American Soraya Vorster, 33, and a Frenchwoman aged between 23 and 33.
An elderly British couple and a 47-year-old Thai woman staying in the same hotel as Ms Carter died around the same time, in similar circumstances. Authorities, at the time, said none of the deaths were related.
In another similar case in May 2009, an American woman and a Norwegian woman died after suffering severe vomiting and dehydration at a Phi Phi guesthouse. The cause of death was never determined.