Narrowing down the source of the dinosaur-killer asteroid

Where did the dinosaur-killer asteroid come from?

This is a question of great scientific and titillating public interest. We know that 66 million years ago an asteroid 10 kilometers in size slammed into the Earth just off the coast of what is now the Yucatan Peninsula in the Gulf of Mexico, carving out the 180-kilometer-wide Chicxulub crater and setting off a complicated chain of events that killed off something like 75% of all species on the planet including all the non-avian dinosaurs, so yea...