In another thread a little while ago, somebody pointed out that it's a suspense/action movie rule that if you don't see somebody die for sure, then they're still alive.
Well, what about another rule along the same lines? If a whole group of people gets killed, except for one survivor, then that survivor is the killer. It doesn't matter how unlikely this may seem, how apparently saintly the lone survivor. So then, was Lyrra responsible for the Landorin massacre? Maybe the other kids pushed Jeruh into the river, and she went nuts and slew them all. She does have a tendancy towards homicidal mania under not too dissimilar circumstances. (The later incident seems to have involved a shadow sword, but maybe the sword that Rhue ends up with was around during the massacre.)
I know this sounds like a peculiar idea. I don't believe it myself, but I wanted to put it out there.
(Incidentally, these two rules get combined in the movies all the time. In Mission Impossible, we don't see the team leader die. Ergo, he's still alive; ergo, since he's still alive, he's the villain. Alternatively, in The Usual Suspects, the FBI agent keeps harping on the first rule, thinking Dean Keaton must still be alive, but it's actually the second rule that's in play.)

