They did indeed. It's a bit of a toss-up. To my mind, anyway, it just seems as if the Crusades would be much too recent an event to go on a fresco in a tomb in Northeastern Italy in the 12th century. Then again, since Venice was certainly one of the major shipping points from Europe to the Crusades, it makes sense as well. It's possible, maybe even likely, that it is the tomb of someone associated with the Crusades.