Born in St. Louis, he attended St. Louis University High School and entered the Society of Jesus (the Jesuits) at St. Stanislaus Seminary in Florissant in 1940. He was ordained in 1953 at St Mary’s College in St. Marys, Kan. He pronounced final vows in 1957 in the Basilica of St. Ignatius Loyola in Spain.

After first vows and juniorate studies in Florissant, he studied at Saint Louis University, earning a bachelor’s degree in Latin in 1945 and master’s and doctorate degrees in philosophy. He earned a doctorate in sacred theology degree at the Institut Catholique in Paris, France, in 1957.

Father Maginnis spent most of his apostolic life teaching theology and religious studies at Regis College (now University) in Denver, where he organized and chaired the theology department. From 1986-91, he taught theology and was assistant administrator of the Regis Career Education Program, an extension of Regis College in Colorado Springs. In 1991, he returned to the Denver campus as professor of religious studies. During that time, he taught religious studies to non-traditional adult learners in the Regis College for Professional Studies. In his last years he served as alumni chaplain.

He helped bring Regis theologically into the post-Vatican II era when he created the school’s religious studies department. Along with Father Robert Boyle, a professor of literature, he also developed a music appreciation course.

In other assignments, he served as a consultor for the former Missouri Province (1970-75) and later as provincial assistant for higher education (1979-85). He moved to Jesuit Hall in St. Louis in 2009 as a pastoral minister and retired to a ministry of prayer in 2014.

Father Maginnis donated his body to the Saint Louis University School of Medicine. Survivors include his sister, Jane Musick of St. Louis.