Born Gertrude Irene Mandeville in Jacksonville, Ill., she entered the Sisters of St. Joseph of Carondelet in 1949 and made final profession in 1957. She received a bachelor’s degree in mathematics from Fontbonne College in 1963 and a master’s degree in elementary education administration from Saint Louis University in 1970.

Sister John began her 68 years of ministry as a Sister of St. Joseph teaching grade school at Holy Guardian Angels in St. Louis from 1952-54. She served in elementary education for 40 years, starting in Mobile, Ala. Returning to St. Louis, she taught at Nativity of Our Lord School in St. Louis from 1961-64 and at St. Agnes School in St. Louis from 1964-70, where she also served as principal. She next was a full-time principal at Ste. Genevieve/Valle Grade School in Ste. Genevieve from 1970-80. During her last 12 years in education, Sister John served as principal at St. Margaret of Scotland School in south St. Louis.

After a brief sabbatical, Sister John served the next 10 years at St. Paul Parish in St. Paul as a pastoral associate. She visited sick and shut-in parishioners, served as an extraordinary minister of the Eucharist and worked with the parish council among other duties. While working at the parish and continuing to live at the convent at St. Margaret of Scotland, she and another Sister of St. Joseph began to take in foster children, caring for more than 100 of them for more than 15 years.

From 2013-16, she served her community as a volunteer at Nazareth Living Center.

Since 2016, Sister John had been living at Nazareth Living Center.

Survivors include a brother, Robert Mandeville of Springfield, Ill. Burial was in Resurrection Cemetery.