A fire at a bar in a Swiss ski resort appears to have been caused by sparklers placed on bottles of champagne that came "too close to the ceiling", authorities said.
Forty people died after the blaze in the early hours of New Year's Day in Crans-Montana, while 119 were injured.
Valais Attorney General Beatrice Pilloud told a news conference on Friday the investigation would focus on the materials used on the site, the bar's fire safety measures, its capacity and the number of people inside at the time of the fire.
The investigation will explore whether prosecutions will be necessary. "If that is the case, and if those people are still alive, there will be a case opened against them," she said.
"Everything leads us to think that the fire started from sparkling candles - or sparklers - which were put on bottles of champagne [that were] moved too close to the ceiling. From that, a blaze began very quickly", Ms Pilloud told the conference.
