Of the three men who were murdered, only Brendan Mess was a resident, right? So the other two were visitors. One way that one person can murder three people like this is to do it one at a time.
Brendan may have been at his house alone when the murderer arrived. So he may have been murdered first. Then the other two guys arrived while the murderer was still there, arriving either separately or together. More difficult if they arrived together, but not impossible. Much easier to murder each one separately.
We do not have enough info to know if one or two or all three bodies had "drag marks" on their bodies. (I am assuming this must be a second floor apartment accessed by either exterior or interior steps.) But something made police believe there was dragging involved.
The neighbor believed that five men lived there. Sounds like there were lots of guys about the place a lot. And perhaps lots of cars outside? In fact, did anyone other than Brendan actually live there?
Re: Police writing this off as a drug related murder
Certainly sounds plausible, on the surface at least. But I agree, it sounds like more of a "statement". Wonder if anyone other than the local force investigated? For triple murder, I would hope that State investigators were brought in.
Coincidentally, yesterday I read an article about the sisters. One of them got into a physical altercation with her boyfriend in which she slapped him. Someone called the police - article didn't say who. When police arrived they arrested her for Domestic Violence AND arrested the boyfriend for possession of a "large amount of marijuana" that was found in a closet. (Sorry for no link on this. I read SO many articles yesterday, but I know it was mainstream media.)
It is my belief that the younger Bomber was dealing marijuana and that explains where the money was coming from. And maybe the older brother was doing the same prior to the onset of the hyperreligiosity.