The autopsy results confirmed yesterday that the two construction workers killed when the Hotel Tivoli collapsed in Arenal last Friday, were crushed to death. It has also been revealed that the hotel was built on a septic tank, but engineers are still unable to say what exactly caused Friday's catastrophe. Police yesterday continued taking statements from eye witnesses and builders on site when the three-storey building collapsed and sources revealed that investigators have turned their attention to the structure of the building. One said that it is possible that one of the main supporting walls gave way, having a domino effect on the rest of the building. But earth movement or subsidance caused by the recent rains is still not being ruled out. None of the workers on site when the hotel crashed down have denounced the company which owns the hotel, but because of the two fatalities, the investigation is being handled by the courts. The San Fernando police station has been transformed into a temporary laboratory where evidence removed from the site is being examined. The injured builders admitted to hospital for treatment on Friday are still recovering in hospital, but it is believed that they have been able to speak to police and accident investigators.