Alright so let's lay this out a bit.
My understanding is that the two girls who were not injured lived on the first floor. The couple was on the second floor/main living floor and the two girls who were murdered lived upstairs. Based on the layout of the house it seems you could walk in the "front" door which led into the first floor where the two survivors were or you could enter from the second floor in the kitchen area as the home was on a hill. So two possible entrances and exits.
We know that a "door" was left open. They don't specify which door that was. We also know the 911 call reported an unconcious person. Given the undoubtedly bloody scene and layout of the house, to me this implies somebody was looking into the house and saw a person lying on the ground but could not reach them. As if they had been able to, I don't think it would have been described as an "unconscious" person but rather a murder victim. I also think this means it wasn't one of the roommates who called 911 as they would have been able to access that person. I think it was the downstairs door that was left open as based on the Zillow photos, the "unconscious" person would have been visible on the second floor and if that door was left open, who ever saw the body could have entered the house to check on them. I think the unconscious person was one of the couple who slept on the second floor.
So piecing this together a bit...
The murderer gets to the second floor. Not sure how. Maybe a window was unlocked or maybe the door itself was unlocked. There was no sign of forced entry. They could have either entered and exited from the first floor or entered on the second floor and exited on the first. I suspect the whole house was sleeping. They go upstairs and murder the two girls. I'm guessing it was in their sleep. Then they go downstairs. Now maybe the couple on the second floor heard a noise and was awake and came to investigate? Then the intruder murders them both to protect himself (or herself, I suppose), and one of them is murdered somewhere in view of the door of the kitchen or the kitchen windows. If they were also targets then I guess the murderer could have killed them in bed but one of them tried to run but was killed.
The murderer then flees out the downstairs door and leaves it open. They could have run past the bedrooms down there in a haste to leave or maybe tried the doors but they were locked?
Then time goes by...around noon someone shows up. The rumor is they had plans with one of the survivors but it could have even been a neighbor or someone who walked by. The person comes to the second floor door, which is a sliding screen door, and can make out that there is a person lying on the ground but probably can't see the blood. They call 911 and report an unconscious person. First responders arrive and find the murder scene.
My questions: if there was an open door, why wasn't the person who saw the unconscious person able to enter the house? Unless maybe they didn't try to go around to other, unlocked door? I just assume the door in the kitchen was locked or else the person who saw the body would have tried to enter. If it was a friend of one of the girls alive in the basement, why didn't they call them and tell them to come upstairs and check on the person?
All in all, a lot of questions and my speculation could be completely off. I don't understand how they can say this isn't a threat. Even if there was a specific target, this person obviously has no qualms murdering four people at once. How can you say he wouldn't murder someone else? I also don't think it's odd the two girls slept through it. I suspect most of these individuals were murdered in their sleep so there may have been little to no noise. They were probably out late and could have had music playing or earbuds in. What a horrific thing to wake up to.
JMO.
