Born in St. Louis, Missouri, Leo Steck studied for the priesthood at Kenrick Seminary and was ordained a priest on June 8, 1924, for the Archdiocese of St. Louis. He was engaged in pastoral work as a priest and served as the director of the Catholic Rural Life Conference.[1] On March 13, 1948 Pope Pius XII appointed him as the Titular Bishop of Ilium and Auxiliary Bishop of Salt Lake City. He was consecrated a bishop by Archbishop Joseph Ritter of St. Louis on May 20, 1948. The principal co-consecrators were Bishops Mark Carroll of Wichita and Auxiliary Bishop John Cody of St. Louis.[2]
Steck established the Newman Center at the University of Utah. He also wrote a leaflet, A Foreign Mission Close to Home, that appealed for financial support for the Salt Lake diocese The Mormons misunderstood its intent a considered it a call for the conversion of the members of the Church of Jesus Christ of Latter-day Saints. Salt Lake's bishop, Duane G. Hunt, had to reassure the Mormons of their true intent.[1] Bishop Steck had health problems and when he was in his native Missouri suffered a stroke. He died at a St. Louis hospital on June 19, 1950, at the age of 51.[3]