William Xavier Kienzle: A Priest Turned Master of Mystery William Xavier Kienzle (September 11, 1928 – December 28, 2000) was an American Catholic priest and prolific author renowned for his gripping detective novels centered around Father Robert Koesler—a character that cemented his place in the annals of American crime fiction. Born in Detroit, Michigan, Kienzle’s journey from theological vocation to literary success is a fascinatin…