Good guess people but they were both killed in the mad wenchester bombings in england. when he meet Watari. it hints to it in the Los angeles bb merder case read it its awsome. maybe better than the manga if not close.
posted sa loob ng isang taon na ang nakalipas
Yeah, the BB Murder Case book was really good, but if it isn't mentioned in the manga or anime anywhere (or hinted to) that L's parents died in the mad wenchester bombings in england, then the actual may-akda of death note did not ever specify how L's parents died. You see, BB murder case is not written sa pamamagitan ng the may-akda of Death Note Ohba, but sa pamamagitan ng Nisio Isin as a "fan tribute" I suppose you could say. Therefore, I don't really count any extra info about L in BB Murder Case cause the original may-akda Ohba never intended for that... but that is just me and how I feel. You guys can count Isin's creation on how L's parents died if you want to (but I'm not).
SonOfPein
posted sa loob ng isang taon na ang nakalipas
well, L was raised at the orphanage, so that hints to the fact that his parents died when he was young... though the manga never specifically says what happened to his family.