CHEIRY, Switzerland -- Autopsies on some of the 48 dead in the apparent mass suicide of doomsday cult members in Switzerland showed they received a powerful drug while still alive, an investigator said Thursday.


Examining magistrate Andrei Piller told a news conference in the Swiss village of Cheiry, where 23 of the victims were found, that the theory of a collective suicide had not been abandoned, but some evidence "makes us think of an execution."


At the same time, however, he said some material gathered on the idyllic, isolated Alpine farm where the bodies were found appeared to confirm that the cult members had gone to their deaths of their own free will.


"We found a letter on one of the persons addressed to a member of their family in which they said they were coming to Switzerland to die," Piller said.


A total of 25 other bodies were discovered in the Swiss alpine hamlet of Granges, 160 kilometers from Cheiry, and two were found dead in a house north of the Canadian city of Montreal. All had apparently died Tuesday. The bodies were found Wednesday after fires broke out in all three locations.


Police linked the three incidents to "The Order of the Solar Temple" cult led by Luc Jouret, a Belgian citizen and homeopathic doctor known as a charismatic preacher who warned that the world would soon come to an end.


Piller said police had issued arrest warrants in connection with the deaths in Switzerland, but he declined to say how many and to whom. There was no immediate sign as to whether Jouret or his close associate, Joseph di Mambro, were among the dead.


One former cult member interviewed by a Swiss newspaper said he believed Jouret might have fled Switzerland, taking cult funds with him.


All 48 bodies found in Cheiry and Granges were taken Thursday to a forensic institute in Lausanne, a university town on Lake Geneva, for autopsy. Doctors there said results might not be known for three to four days.


But Piller told the news conference in Cheiry, a picture-postcard community in rolling green hills where cowbells mingled Thursday with a memorial tocsin from the village church bells, that there had been some preliminary findings.


"The signs on the victims make us believe that a powerful product, not yet identified, was administered either by injection or intravenous drip," he added. Three rifles had been found near the dead.


Most of the dead in Cheiry had plastic bags over their heads and gunshot wounds. Nearly all were found lying in a circle, their heads pointed outward, in an underground conference room.


A fireman who brought several bodies out of a partially burned ski chalet at Granges said many of the dead there had "beatific smiles" on their faces as though they were content with what was happening.


In one room, a man and a woman lay side by side on a bed holding hands. In another room, a boy of about six and a teenage girl also lay in a peaceful pose of total relaxation, the fireman told reporters.