I thought he was... right after it happened...
Well, Sasuke didn't EXACTLY kill Itachi... Itachi died of exhastion... *sniff* and the last thing he did was... poke his little brother's forehead... *voice cracks* *cries*
...okay... *recovers* And then Sasu was captured by Tobi... and Sasuke attacks him with MANGEKYO, and then Tobi tells him the whole story...