[3] It has been suggested that Gonzalo and Nuño had engineered the coup that forced Alfonso III to abdicate and put García on the throne in 910.
[4] In 920, Nuño and two other counts, Fernando Ansúrez and Abolmóndar Albo, along with the latter's son Diego, defied King Ordoño II and refused to participate in a defensive war against the Caliphate of Córdoba.
The earliest surviving document to name him as count of Burgos is from the archives of the monastery of San Pedro de Cardeña and is dated 13 September 922, after his release from prison.
[7] Another document from San Pedro dated 25 February 926, early in the reign of Alfonso IV, shows that Nuño had acquired the county of Castile at some point after 922.
[8] A document of 26 March 927 recording a court case involving the monastery of Santa María del Puerto in the port of Santoña is dated to the reign of Count Nuño and King Alfonso Fróilaz.