Mary Clarke grew up in the luxury of Beverly Hills, Calif., where movie stars, such as William Powell, Hedy Lamarr and Dinah Shore, were among her neighbors. She spent weekends at a roomy beach house overlooking the Pacific and once had closets filled with mink coats and ball gowns.
She was married two times, raised seven children and managed her father's office-supply business after his death. In the midst of this busy life, she devoted more and more time to charity, which she considered a crucial part of her Catholic faith.
In 1965, she accompanied a priest on a mission to deliver medicine and other supplies to Tijuana, Mexico. After several other stops, they ended up at the gate of one of the country's most notorious prisons, a state penitentiary called La Mesa. The warden invited them inside to drop off their donations at the infirmary.
She began to visit the prison more often, attending to the needs of the inmates, guards and police, and the transformation of Mary Clarke Brenner had begun. In 1977, when most of her children were grown, she moved to La Mesa.
She made it her vocation to attend to the needs of some of the most destitute and dangerous people in Mexico. She brought them medicine, bedding, clothing and food. She invited doctors and dentists from California to provide medical care. She worked with Mexican officials to improve conditions in La Mesa and other prisons.
When she walked through the halls, prisoners kissed her hand, and she kissed theirs. Notorious criminals confessed to her and pledged to change their lives.
In Tijuana and throughout all of Mexico, she was known as "Madre Antonia" -- Mother Antonia.
She received the blessings of a Mexican bishop of the Catholic Church, was greeted by Pope John Paul II and was commended by Mexican President Vicente Fox. She went on to found a religious order for older women seeking to help the poor.
Mother Antonia went on to live in the prison for more than 30 years, improving the lives of thousands of prisoners, guards and their families. Mother Antonia was the subject of a 2005 book by Washington Post journalists Mary Jordan and Kevin Sullivan, "The Prison Angel," and a later documentary film.
After years of weakening health, she died Oct. 17 at the Tijuana headquarters of the religious order she founded, Sisters of the Eleventh Hour of St. John Eudes. She was 86.
She had heart ailments and myasthenia gravis, a neuromuscular disorder. A daughter, Carol Brenner, confirmed the death.
"Something happened to me when I saw men behind bars," Mother Antonia told the Los Angeles Times in 1982. "When it was cold, I wondered if the men were warm; when it was raining, if they had shelter. ... You know, when I returned to the prison to live, I felt as if I'd come home."
The prison warden, Carlos Lugo Felix, had another name for Mother Antonia: "There is no other way to describe her. She is a saint."