I've thought about this, as well, that it would be a very difficult house to navigate had you never been inside before.It seems as though he MUST have visited the house before (whether when it was "open and easily accessible" for a party or at an earlier time when he may have entered uninvited at night when residents were sleeping).
That 2nd floor is odd in that the flooring is not all at one level on it; there is a step up to the living room from the hall, which is located at the foot of the 2nd-to-3rd set of stairs between the kitchen and DM's bedroom.
One would think an intruder likely to trip or stumble at that point, both when he was moving from the base of the 2nd-to-3rd set of stairs to the living room (to advance to XK's room) as well as when he made his way back out to depart the residence. And particularly so when moving around in semi-darkness as minimal light would have been provided by the "Get Vibes" light (there was one on the wall shared between the living room and bathroom on 2nd floor as well as one on the 3rd floor) and the "fairy lights" on the outside patio.
Even if he familiarized himself with the layout of the residence from online rental or real estate listings, that detail would have been very easy to miss.
I could also see him joining one of the many parties that took place there. Let's hope he did not do that because that would be a great defense since I'm sure they have more DNA on him than was listed in the affidavit. "My client was in the house on at least one occasion attending a party."
However, if he did attend a party, I'm fairly certain a surviving roommate or another partygoer would be able to identify him as being their previously. BCK would definitely not blend into that younger sorority/frat crowd, IMO.