Wenza Ali Mutlaq walked a bit uncertainly up the long street near the main government offices here on June 22, the hot wind stirring her heavy black abaya. She passed the concrete barricades put up to ward off suicide car bombers and made her way alone, almost haphazardly. Suddenly, a police car zoomed in. A policeman got out to talk with her. And then their lives were over — torn apart, along with 14 other people, by the huge blast of fire from her concealed explosive vest. Ms. Mutlaq, who was in her 30s and whose attack was captured on...