I have wondered the same. A mattress and if I remember correctly a nightstand. Yet then we are told or it is implied that the perp did not come into the house past a few feet. Maybe it was just suggested taking more for any possible scenario is better than missing something so they took the mattress?
I also find it a bit contradictory when in the beginning the statement was made the sheriff said it was about the most violent or horrific (or something like that) crime scene he had ever seen and then later we hear it sounds pristine and there is no evidence, no DNA, nothing disturbed and they only entered a few feet and were there a short time, or that is what is suggested anyhow. The statements to me contradict. The only thing i can think of that would make both statements possibly true is if the wounds and injuries from the entry area of the house are really bad, with multiple shots and wounds? And maybe the parents struggling or trying to move and Jayme too. That would leave no forensics to speak of relating to the perp but could leave a violent scene with nothing disturbed. Otherwise, it makes no sense to me, the contradictory statements...