I'm pretty sure nobody on this site, or elsewhere, has with any accuracy, described the scene in any way close to what was in fact found there. I don't think that has been nailed down by any of us. When they say odd, unusual, signatures, not what you'd expect, I think we're all way off the beam in terms of what this killer left behind.
That's just my opinion.
With that being said, I do think he is/was physically fit. I think he is physically strong. Upper body strength. A farm boy, athlete, football player, swimmer, weight lifter. I don't think he has any physical disorder that would be readily apparent walking in a crowd. Keen eyesight, determined, focused, organized, ruthless, murderer.
Anyway, my colleagues, over the years, we've had great discussions relative to the nature/nurture, or determinist/free will debates.
I always like to take the side that believes all behavior is choice. It may be disturbed, or affected, by ones experience, or by drug/alcohol abuse, or chemical imbalance, but the act of behaving remains the choice of he or she that engages in it. For me to believe otherwise means that some other entity has taken over a person, and that person has lost the power of choice in behaving, and has given up that power to some other power that is acting within the person.
I always liked to ask my clients, if you didn't do it, then who did? The answer will give a quick psychoanalysis of the individual, for sure. If the answer is someone else is operating inside me, then a good follow up question would be to say, that's interesting, tell me more about this person. We clearly, at that point, have entered the realm of psychosis, multiple personality disorder, etc.
I will remain confident that BG knew what he was doing that day. He planned it, and acted upon it. He came prepared. I suspect he had the layout of the land all figured out, he was familiar with it. He knew his entry, his exit, his approach, his destination. I just don't think it was random.
And he has nerves of steel. He has kept his mouth shut. Either that, or he is being protected. Or he is dead.
If it is the former, the ability to keep his mouth shut, then IMO he has quite a strong conscience. He knows what he did was wrong, and he wants to avoid the punishment for doing it.