Question 1: When I was in college my roommate & I always locked our doors when we had the opposite s*x over. And given that X's dad recently changed 'a lock' it sounds like X was security conscious i.e., the kind of person to lock her door at night. So, I'm wondering did each pair of victims really have their door unlocked, or did the killer pick the lock?

Question 2: If the killer was familiar with the layout of the house, whether from online real-estate listing sites and/or from a prior visit to the home, then he would have known that there were 6 bd rooms total and a lower lever. Therefore, did the killer specifically choose to kill the 4 victims who ultimately died only, was the door of the room with the survivors locked, or did the killer not know there were 2 more bd rooms?

Thoughts?