While examining one of the prisoners' suicide notes, L discovered part of a message:

L do you know…

He racked his brain hoping that Kira, who he was sure was responsible, would not leave him there.

A second note was found…

Finally! The end to L's puzzling.

Shinigami love apples.

"What?" L found this impossible to believe. "I hate apples!" Unless they're caramelled...

"Not to offend, Ryuzaki," Watari stated. "But I feel I should point out you hate all fruit."

"Not if it's candy covered." L muttered to no one but himself.