Right. But the problem here is that the elders/Danzo wanted to have the Uchiha eliminated because they knew that they were a threat regardless. And Hiruzen let them take control of the situation.
To be honest, it doesn't matter if Itachi knew or not. It'd be impossible for Itachi to prove that it was Obito that did it. The Uchiha clan knew that they were being suspected of the act, it's expected that the clan as a whole denied it (I doubt that they ignored or agreed to it obviously) but no one would believe them most likely. They didn't have evidence. In Itachi's case with Obito, Obito wouldn't accompany Itachi to prove that he was the one who did it. What one says doesn't matter if they don't have proof, Itachi wouldn't have a way to prove it to the public. U_U
Wow. Didn't know that Deidara fans could be worse than Itachi fanboys.
Akatsuki Itachi>Akatsuki Deidara by Kishimoto's databook and the small encounter they had. Not much more is needed to prove that, sadly. Deidara caused his eye to be immune from 3-tomoe genjutsu...not Tsukiyomi. If they were to engage a second time when they were alive, Deidara would foolishly look directly at Itachi, thinking he'd be immune to genjutsu and lose to Tsukiyomi. GG