These are the four traits that come out when you speak to the relatives of Agathe Uwilingiyimana, Rwanda’s first and only female Prime Minister, who was killed by Hutu hardliners on April 7, 1994.

Thomas-Greenfield was staying, as a guest of a fellow U.S. official, in a house next door to Rwandan Prime Minister Agathe Uwilingiyimana. It was April 1994, ...