AMC-When are we going to find out who killed Stuart?

UGGHHHH... I am so ready for them to tell us who killed Stuart! Who do you guys think it is? Today's episode was very interesting... Emma wrote on a chalk board "Mommy" when the DA Willis was questioning her. I'm so confused as to who killed him. I'm starting to believe it wasn't Kendall or Annie! It's probably someone we know nothing about, or who hasn't even been in any of these episodes! I wanna know already! lol... tell me what you guys think... =]