So the camera that caught the thud and dog barking was less than 50 feet from X's bedroom wall, per the PCA. That would be at the apartment building, correct? 500 Queen St? I've seen it posted about one of the nearby houses, but no houses were less than 50 feet from X's bedroom wall. Not that it matters, but basically all that is between that apartment building and X's wall is the narrow road into the apartment complex. I think the thud at 4:17 was almost certainly X or E, due to the proximity and timing. The dog barking could be any dog from nearby that heard the thud. So from that wall we have voices/whimpering, a thud, possible blood dripping down the outside wall (I know, I know, it could be heating oil, but even the coroner said she thought it was blood), SG saying the coroner described a real battle going on in that room, two bodies in or about that room, X by the door and no mention of where E's body was, with BK allegedly pulling out at 4:20.
I just don't think there was enough time for him to then go upstairs and kill two more people, come back down, go back towards X's room for some reason, then head back out in time for DM to see him walking towards her and out the sliding door. Not to mention that the sheath stayed in his pocket during the downstairs battle but fell out on M's bed?
IMO, the 3rd floor had to be first.