One co-owner of a Swiss ski resort bar, Jacques Moretti, has been held in custody after a fire at Le Constellation bar on New Year's Eve killed 40 people. The fire in Crans-Montana also injured 116 people, with many victims aged under 20. Swiss media say Moretti was seen as a potential flight risk. The bar had not undergone safety checks for five years. Moretti and his wife Jessica, both French nationals, are under criminal investigation by Swiss prosecutors. They face charges including manslaughter by negligence, bodily harm by negligence, and arson by negligence, the Valais prosecutor's office said. Prosecutors believe the fire started when partygoers lit sparklers attached to champagne bottles. These ignited sound-insulating foam on the bar's basement ceiling. Switzerland held a national day of mourning for the victims. A minute of silence was observed, church bells rang for five minutes, and trains and trams stopped briefly. Zurich airport also paused operations. In Crans-Montana, firefighters received a standing ovation for their work.