Although the prosecution probably has all they need, I'm thinking they will want to introduce Sam's music and his alter ego to go to state of mind or something. I analogize it to finding borderline child




(as introduced in the Michael Jackson case) in mass quantity in the home of an alleged child sex offender. It could come in.
There is no insanity defense that will hold up, so I don't see how making Sam look like a lust-for-murder satanist can hurt - the jury will despise him. And they won't find it so hard to believe he would use a hammer and maul and do the hideous deed.
I holding out on the belief that Sam did something extra there with the bodies for all those days. When I think of Sharpie, I think of writing on people; on skin, or on walls. Have you never sharpied someone who passed out? Ok, you are a nicer person than I am. Why collect only sharpies? There was writing in the spiral notebook - they collected sketch books or something from a chest in Emma's room...I won't be shocked if Sam wrote weird stuff on the walls or on the bodies.