- Kari Bowerman, 27, and Cathy Huynh, 26, died in Vietnam on July 30
- Their symptoms matched others' who have died in Asia: vomiting, low blood pressure, dehydration
- Experts suspect pesticide poisoning from a spray used to combat bed bugs in the region
This is all we know for sure:
Kari Bowerman, 27, and Cathy Huynh, 26, were backpacking in Vietnam while on break from their jobs teaching English in South Korea.
On July 30, the friends were admitted to Khanh Hoa General Hospital in Nha Trang. Both were vomiting, had difficulty breathing and showed signs of severe dehydration.
Huynh was eventually released from the hospital. She returned later that night to hear the devastating news -- three hours after being admitted, Bowerman had gone into respiratory failure and died.
Two days later, Huynh was dead.
What we don't know for sure is what triggered their deaths.
The travelers' stories are just the latest in a string of mysterious tourist deaths in Southeast Asia. Investigators with the World Health Organization suspect poisoning is to blame, but determining the origin has proven difficult. Meanwhile, friends and family are desperate for answers.
"It's been a nightmare trying to get information," Bowerman's sister Jennifer Jaques said. "No hospital reports. No police report. No nothing. Whatever happened to her we need to make sure doesn't happen to somebody else."
Not yet determined
Almost immediately, international media reports began linking the deaths to an incident in Thailand in June in which two Canadian sisters died.
A hotel maid found Noemi and Audrey Belanger, 25 and 20, in their room on Phi Phi Island more than 12 hours after their deaths. The sisters were covered in vomit, according to CBC News.
In February 2011, New Zealand resident Sarah Carter, 23, died in Chiang Mai, Thailand, after arriving at a local hospital with low blood pressure, difficulty breathing and dehydration from vomiting, according to the New Zealand television network TV3.
In the Downtown Inn where Carter had stayed, the Bangkok Post says three other visitors -- a Thai tour guide and an elderly British couple -- died between January and May 2011.