WARNING: The following article contains major spoilers for Heroes in Crisis #6 by Tom King, Mitch Gerads, Clay Mann, Tomeu Morey and Clayton Cowles, on sale now.

The mystery of the killer, or killers, responsible for the massacre at Sanctuary has been unfolding since Heroes in Crisis #1. In Issue #3, though, at least part of the mystery was solved when Harley Quinn was shown to be the responsible party for the murder of Wally West.

Or so we thought.

Tom King, Mitch Gerads and Clay Mann's Heroes in Crisis #6 revisits that moment, but with a surprising twist. Oh, Harley Quinn is still shown to be at the scene, as is Booster Gold, but the specifics have been changed. The variant scenario throws into question not only who's behind Wally's murder, but the whole range of possibilities regarding other potential assailants.

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What Happened, Then and Now

In Heroes in Crisis #3, Wally was seen on Sanctuary's front steps, cradling the body of his fellow Titans teammate Roy Harper (Arsenal). As the flashback unfolds, Wally laments the consequences of his recent return to reality, then he is coldcocked from behind by the mallet-wielding Harley. No sooner does this happen, Booster arrives, seemingly unsurprised by and emotionally detached from all the murders that just occurred.

In the current issue, Wally is again holding Roy's body in his arms, but he's curiously now inside the confines of Sanctuary, rather than on the front porch. The reason for his emotional distress is unchanged, but he's once again clocked from behind. Only this time he's fried by Booster, not Harley. And this time, it's Harley who happens by immediately after. Harley also demonstrates the same kind of ambivalence as Booster.

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So Did They Do It, or Not?

This new new sequence of events throws the validity of the original into question. The divergent and conflicting scenarios introduce the possibility of imagined realities, and that nothing shown within the context of the story can necessarily be construed as "real." But then, taking a step back, Harley and Booster's respective questionable states of mind make this possibility a little more plausible. If nothing else, one aspect that's now fully understood is why each blames the other for the massacre.

Harley always seemed like too obvious a culprit anyway. Her villainous background practically eliminates the possibility, as a troubled villain entrenched among similarly troubled heroes doesn't make for much of a whodunit mystery. Plus, superhero mass murder has never seemed to be her style. And solving such a mystery only a third of the way through the story wouldn't leave much room for future intrigue.

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Conversely, despite Booster's current troubled mental state, he's historically been a superhero, and murdering his colleagues doesn't seem to be his M.O., either. While there's precedent for good guys breaking bad in the DC Universe -- like his former boss, Maxwell Lord -- Booster just never seemed to carry much villainous potential. And like the seeming revelation about Harley three issues ago, a similar one regarding Booster also seems premature.

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What Does It All Mean?

It all likelihood, neither of these overly obvious suspects is the culprit, despite all indications and appearances. In fact, nothing in the storyline has even indicated that the massacre is the work of a single killer. If anything, there are clues that multiple killers are involved. Two-thirds of the way through the series, there remain more questions than answers.

Prior to the killings, Sanctuary was populated with numerous heroes facing emotional and psychological difficulties. While the spotlight has been on Harley and Booster, it seems likely that there are mysteries outside the range of the spotlight's glare. Could one of the more obscure characters somehow be behind it all? As implicitly posited in Flash Annual #2, is there more to Wally's murder, something to do with time travel? Or, with three issues remaining, is there some deus ex machina waiting to be unveiled?

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Look Within

There are elements within the storyline itself that are worth considering, though. The virtual reality chamber that's used by various characters for therapeutic or cathartic purposes is just that -- virtual. Perhaps the two scenarios shown for Wally's murder so far are simply byproducts of that virtual reality experienced by Harley, Booster and anyone else for that matter, meaning that the actual circumstances behind Wally's murder have yet to be exposed.

And there's the character who's been the elephant in the room throughout the entire series, the Psycho Pirate. The masks of anonymity provided to Sanctuary's residents immediately evoked similarities to the mask worn by Psycho Pirate, similarities that have thus far been unexplained. Harley is shown wearing one of these masks, or perhaps Psycho Pirate's actual mask, on the current issue's cover. Psycho Pirate has also been a prominent character in Tom King's Batman run, which seems more than mere coincidence.

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So, maybe Harley killed Wally. Or maybe it was Booster. Or maybe it was someone else. Maybe Psycho Pirate manipulated them or other characters into committing murder. Or maybe Wally isn't even really dead. Regardless, everything we thought we knew about Wally's apparent demise has been upended.

Also, let's not forget about the artificial intelligence that controls Sanctuary. Could there be some kind of Brother Eye/Hal-9000 malfunction behind all the chaos?

The mystery continues, and possibly even deepens, in Heroes in Crisis #7, on sale Mar. 27.