Torquemada must have been consulted at this point and probably gave the same advice. It was he that the King and Queen commissioned with Cardinal Mendoza, to write a petition to be sent to Rome, asking the Pope for the necessary authority. This document was read and approved by a Junta of nobles, lay and clerical, before it was despatched.
On November 1, 1478, Pope Sixtus IV wrote a Bull which makes plain the sort of picture that must have been painted for him by the representatives of the Spanish monarchs at Rome.
require that as far as we can in the sight of God, we grant your requests, particularly those which concern the exaltation of the Catholic Faith and the salvation of souls. From your letter recently shown us, we learn that in various cities, sections and regions of the Spanish Kingdoms, many of those who of their own accord were born anew in Christ in the sacred waters of Baptism, while continuing to comport themselves externally as Christians, yet have secretly adopted or returned to the religious observances and customs of the Jews, and are living according to the principles and ordinances of Judaical superstition and falsehood, thus falling away from the true orthodox Faith, its worship, and belief in its doctrines. They have not feared, nor do they now fear, to incur the censures and penalties pronounced against the followers of heretical perversity under the constitutions of Pope Boniface VIII, our predecessor of happy memory; and not only do they themselves persist in their blindness, but they also infect with their blindness those born of them, or having communication with them, and their numbers increase not a little. And because of their continued crimes, they weary our forbearance, as is piously believed, and that of the ecclesiastical prelates who are expected to look into such matters, by their wars, by slaughter, and by other evident injuries to men, endured by God, in despite of the aforesaid Faith, to the peril of souls, and the scandal of many. For this reason you have caused humble supplications to be addressed to us, that so pernicious a sect be totally uprooted in the said Kingdoms…
Rejoicing in God over your praiseworthy zeal for the safety of souls, and hoping that you will not only drive out this falsehood from your realms, but that, also, in our times, you will reduce to your rule the Kingdom of Granada and those adjacent places where infidels live, and through the divine mercy will convert the infidels to the true Faith, so that what your predecessors, on account of various obstacles, were denied, may be accomplished by you, and your glory be crowned with that eternal beatitude which is the reward of a vow well kept, we therefore, wishing to grant your petitions and to apply to these things the suitable remedies, are desirous of granting your supplications and permitting three—or at least two—bishops or archbishops, or other men of good reputation who are secular priests or religious of the mendicant or non-mendicant orders, men above forty years of age, of good conscience and praiseworthy life, masters or bachelors in theology, either doctors in canon law or licentiates carefully examined, God-fearing men, whom you may cause to be selected in various cities and dioceses of the said Kingdoms, to take action straightway concerning those accused of crimes, and those who conceal or aid and abet them, under the usual jurisdiction and authority that law and custom allow to Ordinaries and Inquisitors of heretical depravity.