[1] In 1516 he, with several other Dominicans, wrote a letter to Las Casas on the rapid disappearance of the Indians of the Antilles, concerning the numbers of the aboriginal population, and the excesses thought to have been committed by the Spaniards.
In 1518 Betanzos and Pedro de Córdoba attempted to establish a mission on the island of Margarita, but extreme hostility of the indigenous people forced the Dominicans to return to Hispaniola.
[2] According to Franciscan fray Gerónimo de Mendieta, Betanzos did not know any native language and had little to do with Indians, his time being absorbed by administrative duties.
[3] Tomás de Berlanga almost immediately claimed that it belonged to his newly founded province of Santa Cruz with the provincial seat at Santo Domingo.
In his classic work on the evangelization of Mexico, French scholar Robert Ricard called Betanzos zealous, "an impetuous character, not well balanced, but not without intelligence" with a passionate temper.
In the "Opinion" (Parecer) given by him in 1541, and approximately repeated in 1542, just as the New Laws limiting the encomienda in the Indies were to be promulgated under the influence of Las Casas, he took an entirely different attitude.