According to Plan

Kira had the perfect plan to fool the task force, prove his innocence and get rid of L once and for all. There's only one person's interference he didn't account for, and that's his own. Light Yagami is no fool, and he isn't about to play into anyone's hands - not even his own. (AU from Yotsuba Arc onwards where Light figures out that he is Kira. Light/Kira character study.)