Stating the obvious, but he likely had some form of psychosis.
I don't know if I'm remembering the details accurately, but I seem to recall in the reporting after his arrest that there was an alleged incident a few years prior to the murders in which he got angry at a waitress/bartender for rejecting him. He reportedly showed up at a bar (alone), tried to hit on some female employee (awkwardly), and got demonstrably angry when she/they told him there was no interest beyond serving him. I think he had to be asked to leave, if I recall correctly.
Assuming that account is accurate, that to me is a red flag. It's someone who's isolated and frustrated and seems condemned to a life of involuntary celibacy (i.e., an incel). I've read that for many serial killers, particularly when males are the perpetrators and females are the victims, the motive is having a sense of power and dominance over their victims. It's a desire to act out in ways that make the perps feel like they have power to compensate for the apparent lack of it in most of their everyday interactions.
Maybe I missed it, but I am wondering what his connection is to the victims. My common sense tells me that he must have had some sort of encounter with them at some point, even if from afar or even if it were nothing more than a momentary encounter that nobody except Kohberger thought had any significance.
