Yeah, there was a part early in the story (Death Note obviously) where Kira almost gave himself away but L never bothered notice it. Anyone would've thought of it including YOU.

Early in the story, Yagami Light thought that since he's so smart he can hack into his Dad's computer (which happens to be Japan's Chief of Police) and snoop into criminal files to continue his "Judgements." But obviously, this is the part where L could've gotten Kira - BIG TIME. Considering that L has access to the most sophisticated technologies in the world AND he knew first hand that Kira hacks police files, he could have just monitored the traces of access in the police's computer system. No matter how good a hacker Kira might be, HE IS STILL USING HIS OWN COMPUTER TO HACK. And FYI, that's a big NO when hacking. Any efforts of concealing personal information regarding his computer is futile because THERE WILL ALWAYS BE TRACES. Date and time of access, Logs, IP address perhaps. L is a smart person and everybody knows that. L should've used whatever high-tech thingamajigg to gather those traces - concrete evidences that will lead to Light as being Kira.

Unfortunately, L had to ignore this one big opening to prolong the story and be popular and die XP.

Whatever violent reactions you have or reasonable arguments regarding my opinion about Death Note are very welcome.