I was just hit with a thought.
Well, first of all, my current theory on Lilly's murder is that her mother did it. And I think that's why all of Keith's signs were pointing to Jake Kane, because she used his connections. Like Clarence Weidmann, who I'm fairly positive that she hired to threaten Veronica and kick Lianne Mars out of town. Also, I think she was highly resentful of her own daughter, and really had the biggest motive.
But I had a thought. What if Lilly was killed by someone who thought she was Veronica? They were very obviously wearing the same outfit that day, and maybe that's the reason the producers decided to have Veronica's hair long in flashbacks. Although the only thing that doesn't quite add up with this is that Lilly was killed at her own house, so why would they think she was Veronica? Unless, Veronica was supposed to be there. Do we know that or not?
I'm intrigued. God, I love this show.