Catholic Online Saints - Terry Matz answers the question, "Whatever happened to St. Christopher?" - http://www.catholic.org/saints/saint.php?saint_id=36
Military Martyrs: St. Christopher - "Origin of Cult" reads like a detective novel, and suggests that St. Christopher and St. Menas are the same person, a soldier martyred in 308. Images, translations of three early passions, the cult of St. Christopher today, bibliography, links. - http://www.ucc.ie/milmart/Christopher.html
Catholic Encyclopedia: St. Christopher - Article on this martyr, probably of the third century. Although Christopher has been a center of popular legend since the sixth century, all that can be known for certain is that he was a great martyr. - http://www.newadvent.org/cathen/03728a.htm