His parents were Juan Sainz y María Antonia Bencomo.
In 1914, he was offered the Archdiocese of Santiago de Cuba and refused.
Adolfo Alejandro Nouel Bobadilla, Archbishop of the Archdiocese of Santo Domingo assisted by Mons.
Manuel Ruiz y Rodríguez, Bishop of the Diocese of Pinar del Río, and Mons.
Bishop Sainz died in Matanzas on 14 March 1937 and was buried in Necropolis de San Carlos Borromeo.