Ignatius Loyola, the founder of the jesuits, was a jew that "converted" to Catholicism in order to avoid getting kicked out of Spain. The jesuits were set up to help jews gain safe passage out of Spain.
Ritual murder was one of the chief factors, if not the decisive one, in the decision of Fernando and Isabel for the expulsion of the Jews from Spain.
William Thomas Walsh,
Isabella of Spain, page 441.