Born Josephine Pittari in New Orleans, she attended high school as an aspirant at the School Sisters of Notre Dame in St. Louis. Following graduation, she remained in St. Louis as a candidate at Sancta Maria in Ripa in 1956. She was accepted into the congregation as a novice in 1957 and received the name Mary Thomasette. She professed first vows in 1958 and final vows in 1964. She earned a bachelor’s degree with a major and minor in Latin and Spanish from the former Notre Dame College in St. Louis in 1960.

Sister Thomasette taught elementary grades in Louisiana and Texas and at an SSND boarding school in Mississippi. For the next 10 years, she assisted in the Latin American Apostolate of the Archdiocese of New Orleans teaching English, acting as interpreter, and assisting families in their resettlement.

Her next ministry was as a Spanish-speaking, Catholic presence in a new federal prison in the Louisiana Lake Charles Diocese. By 1987, the part-time diocesan ministry evolved to a full-time staff chaplaincy in the federal prison system. Sister Thomasette did religious counseling, assisted with the Catholic liturgies and provided for the needs of all religion groups in the prison population.

Within the year, the prison was populated by nearly 1,000 people from the Cuban Mariel boatlift. Some were there just for placement in American society. In 1987, the State Department announced the deportation of 1,000 Cubans. This greatly upset the Oakdale Cuban population. The hostage-taking, prison-burning stand-off that followed was a worldwide news event. “My 16-hour-day involvement at this time entailed providing religious support for families of the hostages and for staff,” Sister Thomasette said. “I was also translator for the hospitalized inmates and injured staff … During the eight-day standoff, I came to realize that the federal prison system was family; we supported each other.”

She also was grateful for the support of the SSND community. She later served in federal prisons in Texas and Florida. After retiring, Sister Thomasette taught for five years in Louisiana. She then tutored children in Texas before retiring first at Sancta Maria in Ripa in St. Louis and in 2017 to Mississippi and then later in Louisiana.

Sister Thomasette was a long-distance runner, participating in a number of marathons.

Survivors include a sister, Marie Borim of Riverdale, Georgia, and a brother, Thomas Pittari of Pearl River, Louisiana. Burial was in the School Sisters of Notre Dame Cemetery in Chatawa, Mississippi.