The other day, University of New Brunswick librarian uncovered an original Star Wars script which proved that Han Solo (Harrison Ford) shot Greedo first.
To finally put this "who shot first" debate to bed, Peter Mayhew, who played Chewbacca, has posted his own version of the Star Wars script. You can read it below, but it also verifies that Han shot first.
The 1997 special edition of the film reworked the scene so that Greedo shot at Han first, and Han killed Greedo in self-defense. Director George Lucas has said multiple occasions that he originally intended for Greedo to shoot first, but these scripts suggests otherwise.
Star Wars: The Force Awakens opens in theaters December 18, 2015.