The Norwegian Biathlon Federation has published a press release stating that when Zivert was found dead, he was wearing a hypoxic mask. This mask restricts the airflow (oxygen) to the lungs using valves, thereby simulating training conditions at high altitudes. "The Norwegian Biathlon Association currently has no information regarding the circumstances of the acquisition and use of this mask. In the coming days, the association will attempt to clarify the actual circumstances of this case," the press release states.