There was no *trigger*. The killings were planned ahead of time. I don't see the victims as *personal* targets per se....just vulnerable targets to satisfy the urge to kill. Did the killer know exactly how many ahead of time? Hard to say, but I don't see this as relevant in this case. It was a crime of opportunity. Well planned by a very capable killer.
The fact that case remains *cold* shows a killer who knows how to evade LE. MOO.
I think that the killer is on his path to become a serial one, although it might have been his first murder/s. Or more likely, there was someone before, but it was a vulnerable person (an addict, or a sick and old one) who disappeared and has nor been found/connected. Whoever mentioned the
reservations might be right.
This case might have had a "formal" provocation, but IRL the provocation was merely the justification to kill. "Talking sh.@ about us", for example.
I think the person enjoys the hunt. He is not necessarily an avid hunter, but going through the house to find victims was fun for him, maybe more so than the killing. I think that for him, the endorphins rise with anticipation. So even if he is the hunter, the fun is in finding the animal who hides, more than the pursuit. (Maybe something about hunting the animals capable of mimicry, or the ones that hide in burrows?).
He did plan. Probably he had several plans and houses in mind. This one, for some reason, worked the best. I don't think it had to do with KG being in the house, or not. It could have been linked to the frat quarrel, but only because it was a good pretext - murder of X@E that night would have been blamed on that quarrel. I don't think the person was involved in the quarrel, but either he saw it, or heard about it from someone else. (There probably is a "gossip radio" in frat?).
He also understands that the more people, the longer to investigate the connections. One X would be her exes, her family, maybe someone from the sorority. X + M + K = the same for the three, plus verifying K's stalker. E = him and his twins, at least.
I honestly think that he spared the victims downstairs because killing them would have helped identify him sooner, if it makes sense. Maybe it is someone who knows the survivors' friends.
To me, it seems that he worked alone. Maybe there was a scout outside, but unlikely. If someone gave him a ride, this person is either gone, or listed as disappeared, or is hysterically afraid of him. Not a partner in crime.