There are many speculations of how Elisa died because of the condition that she was found in the water. It looks as though she was a victim of foul play because she was found nude with her clothes in the tank with her. The problem with this theory is that when the coroner did the autopsy report, he noticed there were no signs that would lead him to believe she was murdered in any way. There were no scratches, bruises, or marks that show sign of struggle and all tests came back negative for rape. There were not even traces of drugs or alcohol in her system, so it is very hard to believe that she was murdered or raped. Although it does seem a bit strange that she was nude, there is a better explanation for her clothes being off than rape. If Elisa had wandered into the tank while hallucinating but then came back to reality and realized what had happened, she would most likely have taken her clothes off to make it as easy as possible to tread water. If she truly had been raped, it would have been very unintelligent of the murderer to throw the clothes in the tank because their DNA would have been all over the crime scene.