The Army was one of 28 government agencies authorized to fly helicopters near Ronald Reagan National Airport before its Black Hawk helicopter collided with an American Airlines passenger jet last week, killing 67.

Police arrested a “strong person of interest” Monday in the brazen Manhattan killing of UnitedHealthcare’s CEO after a McDonald’s employee in Pennsylvania alerted authorities to a customer who was found with a weapon and writings linking him to the ambush.

The masked gunman who stalked and killed UnitedHealthcare CEO Brian Thompson outside a Manhattan hotel used ammunition emblazoned with the words “deny,” “defend” and “depose,” a law enforcement official said Thursday.