I think I'm with you, CC, and the others in the "yeah, well, Adnan probably did it after all" camp (either that, or random serial killer guy), but there is a Jay motive. Everyone says he was screwing around on girlfriend Stephanie, and while Adnan was willing to not get in the middle of that or tell Stephanie, the series makes somewhat clear that Hae was not the type to so willingly turn a blind eye (planned to confront Jay about it, or tell Stephanie, etc.). So maybe Hae and Jay run into each other that afternoon, she goes crazy on him about the cheating on Stephanie (because: teenagers), he's high and freaks out, and the next thing he knows he's got a dead body to deal with. Total speculation, of course, and I'm really hoping Koenig doesn't try to sell us on any specific answer in the last episode because that would ruin the storytelling up to that point, but there is at least a Jay motive out there.

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