The mystery of what led to the deaths of two vacationing American sisters in their tropical island villa likely won't be solved until investigators see the results of toxicology tests. Annie Marie Korkki, 37, and Robin Marie Korkki, 42, were found motionless in the bed of their villa last week by hotel staff at a resort on Seychelles' main island. Autopsies conducted Wednesday determined the Minnesota natives died from acute pulmonary edema, or fluid in their lungs, according to a police report obtained by Minnesota television station KARE. Police said the women were seen drinking and were helped to their room by hotel personnel the night before they were found dead. Viral infection could cause both pulmonary and cerebral edema, Lank said. "When two dead people are in a hotel room there are a few possibilities that come to mind," said Bruce Goldberger, chief of the Division of Forensic Medicine at the University of Florida College of Medicine. Baltimore-based medical examiner David Fowler of the College of American Pathologists said a good forensic lab will be able to answer many questions.