There is an interesting thesis here and some suggestive evidence. Will have to look up some of the articles referenced.
Was Columbus secretly a Jew? – CNN.com.
Recently, a number of Spanish scholars, such as Jose Erugo, Celso Garcia de la Riega, Otero Sanchez and Nicholas Dias Perez, have concluded that Columbus was a Marrano, whose survival depended upon the suppression of all evidence of his Jewish background in face of the brutal, systematic ethnic cleansing.