"With energy and connections, it was inevitable that Torquemada should rise to power. After studying theology at the Dominican convent of San Pablo in Valladolid, he became prior of Santa Cruz convent in Segovia. He also became confessor to the royal court.
There he whispered in the ears of King Ferdinand and Queen Isabella that many Jewish converts were secretly practicing Judaic rites while outwardly pretending to be Christians."
As long as they remained Jews the Inquisition had no jurisdiction over them. So they didn't go after Jews, per se, they went after heresy within the Catholic Church.
Now if you want to talk about the state policy of the Spanish crown toward Jews, how Torquemada influenced it, and how it caused many to feign conversion in the first place, ok, but that's a different story from the Inquisition proper.