Hi, Oddball-. No, I'm not at all a literal minded man. I wrote to you there was a possible good reason; and you've stated it.

But my problem with breaking the Fourth Wall in this instance would still be this: What you gain in intellectual provocation ("Consider the killer is still unidentified and free"), I believe you lose by the character acknowledging he is in a work of fiction, which calls into question everything in the narrative, including the characterizations, which become possibly specious or the product of an "unreliable narrator/observer." Are the "movie's facts" even the Historical facts? Is this just a "Based on a True Story" ruse like in Fargo? (You never seem to want to concede that the purpose of breaking the Fourth Wall is for the character to acknowledge --with either a wink or a prod-- that he exists within an artificial framework, operating on a "fictional" stage: It's the character himself admitting this is "just a movie" --which I think makes it easier to not ask any of those important questions you brought up about the actual case. (Did it make you look into the true "history" of this story?)

Also: Compared to the "deep crimes" that the Director is examining via the use of the "surface" crime, the identity of the murderer pales next to the identification of the actual "official criminality" that the film chiefly intended to reveal: Police who were foolish, ignorant, superstitious, lacking in modern procedural protocols; and who were willing to frame people, plant evidence, torture-out false confessions, as well as serve to physically oppress the populace as a violent force of the military dictatorship of Chun Doo Hwan. Those are the crimes this film is meant to identify, and for which Park and Cho are, themselves, responsible.

Whereas, the exact same questions you suggest about the "whereabouts and identity of the killer" arise in the audience simply by having the character, in the penultimate shot, left "doomed" to forever ponder those exact points --and showing him in a way that invites the viewer to empathize with his plight, to share in the nature of the dilemma without bifurcating the effect into "emotional"/"intellectual." In Cinema (and virtually all forms of Theater) the purely Emotional (from which ideas can later be understood) always trumps the propagandistic effects of "Intellectualizing" one's point --which can easily be shrugged off as mere didacticism. (As I'm sure you're shrugging off all my blather.) In other words, you still have those very thoughts without the taint of "artifice" having been revealed (which, again, is the purpose of breaking the Fourth Wall). And why do a meta visual "break" --when, literally, the same questioning points are made with the onscreen (coda) graphics?

I still don't believe Bong Joon-ho's Film Language in this work supports your interpretation; but I'm very glad you seem to love this film deeply enough to really think about its implications and effects. I do as well. Maybe our interpretations will find a more insightful middle ground from this banter. Peace out.