Thai officials are saying a young Seattle woman likely died of food poisoning, but her family doubts that conclusion after a pathologist they hired said her lungs were completely congested.

The woman, Jill St. Onge, a 27-year-old artist, died May 2. Her fiancée, Ryan Kells, also a Seattle artist, found St. Onge in their hotel room on the island of Phi Phi on May 2 struggling to breathe.

He rushed her to a local hospital, where she died.

Kells told CNN that he's almost certain his fiancée suffocated to death. "I am not a doctor, but I know when someone can't breathe," he said.

To make matters more mysterious, a Norwegian tourist who was staying in a room next to St. Onge, Julie Bergheim, suffered similar symptoms just hours later and died.

Thai media quoted police saying they are focusing on food poisoning from seafood. Maj. Gen. Pasin Nokasul told the Phuket Gazette that his department was still waiting on lab results to make a definite conclusion.

But Kells said if food poisoning was the culprit, St. Onge and Bergheim, 22, would not have been the only victims.

Dr. William Hurley, the medical director of the Washington Poison Center, also has his doubts, he told CNN. He said food poisoning usually takes days to kill and the person typically dies from dehydration.

Kells said there was a chemical smell in their room. He thinks he avoided becoming ill because he spent less time in the room than St. Onge.

This week, the Phuket Wan newspaper reported that investigators went to the hotel, Laleena Guesthouse, to take samples of the rooms and from air conditioning units. The owner of Laleena vehemently denies anything in her rooms killed the two women.

Kells and St. Onge were in the middle of a three-month vacation through Southeast Asia. They became engaged on the trip.