ahh first post.
Anyways, I think theraflu is right, Adnan knows way more than he's letting on. Jay seems like a sociopath imo. I think it was Adnan's idea to kill Hae and he payed Jay to do it. But remember, Jay was dating Adnan's close friend stephanie, and it was her birthday, so Adnan lent jay his car to buy her a gift.
If that's true, why doesn't he have a solid alibi? And moreover, why would Jay have implicated himself at all in this business if he were the actual killer? Adnan would have either accused Jay of doing it, or confessed to paying for the hit to turn the tables on Jay, and either way Jay would have gotten a life sentence.