However, Thailand police said Sunday that it did not appear that the two were murdered.
Police Lt. Col. Jongrak Pimthong said there was no sign of a homicide, noting the door of their hotel room had been chained from the inside and the sister's belongings were still there.
Audrey Belanger, 20, and Noemi Belanger, 26, were both of Pohenegamook in eastern Quebec, near the border with Maine, according to a cousin reached by phone.
He said the pair studied in Quebec City with their eldest sister, but worked at the family store in the community of roughly 3,000. The cousin, who didn’t want his name used, said word of the sisters’ death had rocked the close-knit community.
“Everyone knows each other here,” he said.
The bodies of the sisters were taken from the Phi Phi Islands to a hospital in Krabi, on the coast of the Andaman sea.
A nurse reached by The Canadian Press at the hospital said a doctor had examined the bodies but did not notice any abnormalities, and that an autopsy would be necessary.
The Phuket Gazette quoted a spokesman with the Phi Phi Island police saying they received a report Friday night about two tourists’ bodies being found in a room.
The Gazette said the sisters checked in to the Phi Phi Palms hotel Tuesday.
The newspaper reported on its website that the two went out that night but stayed in their room all day Wednesday. Apparently by Friday, hotel staff became concerned and went into their room to check.
Poisoning is suspected in the deaths but tests are being done to try to determine the cause of death. The Manager newspaper website quoted police Lt. Col. 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.
The island has a reputation for a party destination with a lively nightlife.
In a 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.
Foreign Affairs confirmed the deaths but did not release any names. A spokesperson said consular officials have been in touch with local authorities.
The cousin said the women’s parents were notified while visiting their other daughter in Quebec City.
The tragic news then trickled back to the Marche Bonichoix, the family store where the sisters worked, an employee said, but would not comment further for fear of upsetting the family.
Messages posted on Noemi Belanger’s Facebook page earlier wished the young woman and her sister a great trip and told both to take care of themselves.
Also on HuffPost