Luigi Mangione, the man accused of gunning down a health insurance executive in Manhattan, plans to argue at his murder trial that he was undergoing an extreme mental health crisis at the time of the alleged killing, a judge revealed at a hearing on Wednesday. The strategy poses steep legal hurdles but could lead to a jury convicting Mangione of the lesser crime of manslaughter, which carries significantly lighter sentences. Mangione, who appeared in court in a dark suit and white shirt, is...