Credit: Richard Foreman/ABC Family Channel © 2010 Disney ABC Television Group Photo: Pretty Little Liars Halloween Episode: Alison Looks Creepy in Costume

We've always been suspicious of the uber-creepy NAT club on Pretty Little Liars  — anyone who gets their kicks by secretly taping teenage girls is pretty messed up — but after Season 2, Episode 17: "The Blond Leading the Blind," the evidence is stronger than ever that NAT killed Alison (Sasha Pieterse).

However, is that really what happened? We're still unsure. Here are our arguments for both sides of the story. Check them out, then let us know what you think happened:

NAT Club did kill Alison: At this point there is both motive and opportunity. We know that the NAT club was around the night Alison died, and we know she had their tapes. We also know that Jenna (Tammin Sursok) had ample reason to hate Ali, while Ian (Ryan Merriman) was generally unstable and bloodthirsty. It's not hard to imagine how the NAT club's attempt to get the tapes back could spiral out of control, eventually ending in Ali's death. This would explain why Jenna and Garret (Yani Gellman) keep such close track of the Little Liars, and why Jason (Drew Van Acker) seems so emotionally broken — being involved in your own sister's death, even tangentially, is enough to mess anyone up.

NAT Club didn't kill Alison: Honestly, we don't have a strong argument against the theory, except that it seems too simple. Maybe we're seeing all of the pieces come together to form a clear picture, but this is Pretty Little Liars, so we're always waiting for that one last twist. Plus, why would "A" pin the murder on Ian if he really was involved with it? That seems far too useful and, well, moral, for our favorite serial stalker.

What do you think? Vote in our poll, and weigh in at our Facebook page.