Alberto Beretta was born Enrico Beretta on August 28, 1916, in Milan, into a deeply Catholic family of thirteen children (of whom eight survived). His parents, Alberto and Maria de Micheli, were committed members of the Secular Franciscan Order, and their home was marked by fervent prayer, sacrificial love, and encouragement of vocations. Growing up, Enrico and his siblings were immersed in faith and service—his sister Gianna would later become a doctor and saint—while he himself pursued studies in medicine, graduating with honors from the University of Milan in 1942.

After completing medical school, Enrico discerned a call to combine healing and evangelization. He began theological studies in Switzerland and later in Italy, then joined the Capuchin Order, taking the religious name Alberto Maria. Ordained in 1948, he was sent to the remote region of Grajaú, Maranhão, in Brazil, where he labored for decades as both physician and missionary. There he built a hospital, founded a home for persons with leprosy (Vila San Marino), visited patients in distant areas, and celebrated Mass daily in service to both body and soul.

In 1981, during his mission work, he suffered a severe stroke that left him partially paralyzed and brought him back to Italy, where he spent his remaining years under the care of his Capuchin community. He died on August 10, 2001, in Borgo Canale, Bergamo.