NEW YORK (AP) — Nearly four days after the shooting of UnitedHealthcare CEO Brian Thompson, police still do not know the gunman’s name or whereabouts or have a motive for the killing. But they have made some progress in their investigation into Wednesday’s killing of the leader of the largest U.S. health insurer, including that the gunman likely left New York City on a bus soon after fleeing the scene. The also found that the gunman left something behind: a backpack that was discovered in Central Park. Police are working with the FBI, which on Friday night announced a $50,000 reward for information leading to an arrest and conviction. (Photo: AP)