The search was for evidence related to the egging, so the police were looking for eggs and other evidence that can confirm Bieber's involvement. Lil Za got nailed for the E (and maybe Xanax?) because they were his and he's an idiot. I did smirk when someone was imagining them all running around trying to flush EGGS down the toilet and leaving the drugs
Bieber will eventually get nailed for something. The way he's been going, there's no way he won't.