The indication of the Jewish-Converso ancestry of the Gutiérrez de la Caballería family was first uncovered in a 1948 article by Norberto de Castro y Tosi entitled "Verdadera Paternidad de Alonso de Estrada."¹² For centuries, historians, without much further investigation, have passed on the rumor that don Alonso de Estrada was an illegitimate son of Rey don Fernando II, El Católico, of Aragón as mentioned by the early historiagrapher of Nueva España, Bernal Díaz del Castillo.¹³ Castro y Tosi presented evidence to the contrary as found in the "pruebas de limpieza" (proof of the purity of bloodlines) of don Jorge de Alvarado y Villafaña, a great-grandson of don Alonso de Estrada and doña Marina Flores Gutiérrez de la Caballería. The information from the "pruebas de limpieza" were gathered in 1584-1585 as part of the requirement for don Jorge’s admission into the prestigious military and knightly Orden de Santiago.

Regarding the Estrada lineage, testimony was taken from relatives of the Estrada family and other residents of Ciudad Real, located about 50 miles south of the city of Toledo. The actual father and grandparents of don Alonso de Estrada were identified from family genealogies in possession of relatives of don Alonso.¹⁴ The outcome of the investigation into the Estrada lineage was the confirmation of their "limpieza". Members of the Estrada family could document they were descended of an "old Christian family".

The admission of don Jorge de Alvarado y Villafaña into the Orden de Santiago was placed in jeopardy when testimony was taken from residents of the Villa de Almagro, near Ciudad Real, regarding the lineage of the doña Marina Flores Gutiérrez de la Caballería, a daughter of don Juan Gutiérrez de la Caballería and doña Mayor Flores de Guevara.¹⁵ It was well known the Gutiérrez de la Cabellería were of Jewish-converso origin. In fact, in 1584-1585, it was still remembered that Men Gutiérrez, the great-grandfather of doña Marina, was tried and condemned by the Inquisition after his death, and his bones had been exhumed and burned by order of the Inquisition court.¹⁶

The "pruebas de limpieza" documents for don Jorge de Alvarado y Villafaña provide somewhat fragmentary genealogical information about the Gutiérrez de la Caballería family. However, when this material is combined with additional information extracted from records of the Spanish Inquisition of Ciudad Real (1483-1485), we can reconstruct a lineage from a Jewish-converso family of the late 1300s, a family known to have practiced Jewish customs and honored Jewish ceremonies after conversion to Catholicism, to the numerous members of one of the most influential and politically powerful extended families of sixteenth century Nueva España, including, doña Beatriz de Estrada, wife of don Francisco Vásquez de Coronado.