This is all very abridged.Originally Posted by justjeffery
Joe Chill was a crook in the golden age story, but was not in the debut Batman story. There was a story where Batman found him and revealed himself to Chill as being the boy whose parents he killed. Batman haunted Chill personally to the point where he went to other thugs and explained that he's created Batman and was under heavy attack. The shocked thugs shot and killed Chill for creating Batman before he could tell them who Batman was. So Batman's secret was safe and the guy who killed his parents was finished.
In the modern age (post-crisis), the story of Joe Chill is found in Batman Year Two. Batman is forced to work with some crooks to catch worse crooks and finds out the guy he's working with, Joe Chill, is the man who killed his parents. You find out there that Bruce Wayne somehow has the gun that killed his parents. Shortly after realizing who and why Batman is, Chill is killed by another villain of the story so Batman is prevented from crossing that line himself.
Later during the Zero Hour story, Batman is back in time. Not far enough to save his parents, but slightly after so he goes straight to Chill's home to fond him. Chill's wife or girlfriend basically says that Chill has been stoned or drunk all weekend and never left the house. I think editorial wanted to return some ambiguity to exactly who shot Bruce's parents. The thinking was if he did finally deal with that one guy, maybe he'd not fight crime quite as hard as he would knowing the faceless killer is still out there somewhere. But it was a Zero Hour story so its debatable for the reader and Batman as to how certain it is.
Due to the first Batman movie, people still believe that Joker or Jack Napier killed Batman's parents. Its not like the information isn't out there if someone wanted to research Batman. People in the theater were like "its Joker" when Chill robbed the Waynes. And some guy in my shop was like "I dunno about this new Batman. They're changing it up so my man Napier didn't kill Batman's parents." *Sigh* I love the general public at large.