CRANS-MONTANA, Switzerland — Investigators said Friday that they believe sparkling candles atop Champagne bottles ignited a fatal fire at a Swiss ski resort when they came too close to the ceiling of a bar crowded with New Year's Eve revelers. Authorities planned to look into whether sound-dampening material on the ceiling conformed with regulations and whether the candles, which give off a stream of upward-shooting sparks, were permitted for use in the bar. Forty people were killed and another 119 injured in the blaze early Thursday as it ripped through the busy Le Constellation bar at the ski resort of Crans-Montana, authorities said. It was one of the deadliest tragedies in Switzerland’s history. Officials said they would also look at other safety measures on the premises, including fire extinguishers and escape routes. The attorney general for the Valais region warned of possible prosecutions if any criminal liability is found. Arthur Brodard, 16, from the Swiss city of Lausanne, was among the missing. His mother, Laetitia, was in Crans-Montana on Friday and frantic to find him.