A U.S. Marine veteran of the Vietnam War, Northrup attributed his cancer to exposure to Agent Orange, a defoliant used by the U.S. military in herbicidal warfare.
Northrup was a member of the Fond du Lac Band of Lake Superior Chippewa. The Duluth News Tribune notes he “was an ardent keeper of Anishinaabe tradition. He and his wife started a summer Ojibwe language camp on the reservation, made birch bark winnowing baskets, took part in the yearly sugarbush to make maple syrup and harvested wild rice on the reservation’s lakes.”