Born May 6, 1929, Fr. Don grew up a parishioner at Sacred Heart Parish in Rock Island, Illinois, where he also attended school through 8th grade. After completing a year at Rock Island’s St. Joseph High School, Fr. Don discerned a vocation to the Missionary Oblates of Mary Immaculate.

From the age of 15, onward, Fr. Done attended Our Lady of the Ozarks, an OMI minor seminary in Carthage, Missouri. He would go on to study at the Jesuit-run Pontifical Gregorian University in Rome, before being ordained to the priesthood on April 6, 1957 at St. John Lateran in Rome.

Fr. Don was the resident priest here at St. Peter’s between 1998 – 2007, before the arrival of the Canons. During the time Fr. Don was stationed here at St. Peter’s the church was replastered and repainted, the roof redone, new gutters installed, and much, much more.

Fr. Dietz lived an incredible life of service to Our Lord and His Church. He served as a theology teacher for 25-years as well as a parish priest for 25-years, serving in the Dioceses of Stockholm, Sweden; Yakima, Washington; Birmingham, Alabama; and of course, Chicago. For many years following his work as a parish priest he served as a chaplain for contemplative nuns and as an assistant to parishes, especially in Spanish-speaking ministry. Along the way, he was named by Pope Paul VI a peritus, or theological expert, at Vatican II, and was made a Doctor of Sacred Theology by the Dominican-run Pontifical University of St. Thomas in Rome.

He lived out his retirement at the Benedictine Planned Living Community in Belleville. Fr. Don will be remembered by many, as a man who served God and touched the lives of His people.