Mary Ann (Mother Mary dePazzi) Lucas, leader of the Sisters of Mercy of Refugio, was born in 1853 in County Cork, Ireland, the younger daughter of George and Margaret (Field) Lucas. Three of the Lucas children dedicated their lives to God in America: a son was a priest in the diocese of Scranton, and Mary Ann and Margaret became Sisters of Mercy in Texas. Mary Ann decided to follow the lead of Margaret, who had been received as Sister Mary Camillus and in 1869 assigned to New Orleans. There Mary Ann joined her from New York and was received as Novice Mary dePazzi on July 4, 1870. New Orleans expanded rapidly, and the Lucas sisters transferred to St. Patrick's Convent in 1871, without realizing that this was their first step on the road to Texas. Two deaths within six months worsened financial and personnel shortages. Camillus inherited the leadership and arranged for dePazzi to profess her religious vows on August 15, 1872. She also sought Irish candidates from New York. Camillus and dePazzi continued their financial struggle for a year before asking Archbishop N. J. Perche to seek a more viable location for them. Perche appealed to the newly consecrated bishop of San Antonio, Anthony D. Pellicer, who invited the Mercy group to Indianola, Texas.
Mary dePazzi was serving as principal in St. Patrick's on January 6, 1875, when she received word from Camillus in Indianola to have the sisters pack and take the next steamer to Matagorda Bay. There mothers Camillus and dePazzi inaugurated their service in Texas when they established St. Mary's Institute early in 1875. The Mercy foundation had advanced steadily by April, when Bishop Pellicer visited the convent for the first reception of Mercy novices in Texas and invited the community to staff the schools in Refugio and San Patricio. Camillus went to New York to gather more Irish candidates, while dePazzi and her charges remained in Texas. A hurricane in mid-September demolished buildings and left hundreds dead. The Mercy sisters found shelter in the Incarnate Word Convent in Victoria, while dePazzi and two companions assisted devastated neighbors to find and bury their dead.
By October 7 Mother Mary dePazzi arrived at the Refugio convent, which, although it was not quite complete, offered refuge to her and the other Mercy survivors. Before transferring to the San Patricio convent in 1876 Camillus appointed dePazzi superior of the Refugio community. The two groups expanded separately. San Patricio moved on to Cuero, Smithville, and Lockhart, and Refugio expanded to Laredo and the Rio Grande valley after the death of Mother dePazzi. Beloved by sisters and townsfolk for a generation, Mother dePazzi led her sisters in visiting the sick, inspiring pupils,and comforting the problem-laden. Her very compassion seems to have involved her deeply in a misunderstanding with the local clergy, especially after she sought a decision from a higher church authority. This appeal resulted in such acrimony and censure that she felt it necessary to withdraw from the area. She left her religious profession for nine years, after which she was accepted in the Mercy community at Mount Saint Agnes in Baltimore. Cancer brought her life to a close on April 11, 1907, and she was buried in the Mercy cemetery in Baltimore.