Hummm....
I do have to wonder.....could motivation have been about rape instead of murder? We actually do not know which means this is possible.
Possible MM was the target. A knife is actually normal to have in a rape to force the victim to comply. The unplanned part was finding KG in the bed then finding XK awake, we know she was awake, she had just gotten the food order.
So yes it is possible this was a planned crime of rape that ended up in 4 murders. And I believe with a planned crime of rape he still would have taken all the DNA precautions with his car which translates to keeping the blood evidence out of his car.
2 Cents
In that case, he was allowing for the use of the knife (IOW, he would not have let his rape victim survive the attack - which is, of course, fairly common in violent stranger rapes).
If what we're all speculating about has any merit, then BK would have fantasized about the rape, but also about murder. IMO, it is unlikely that he was getting any sexual fulfillment with any real human. He would have fantasized about rape as either the only way he could "get sex" or the only way he could become
aroused enough for sex. Not uncommon, either - but most people with these fantasies do not act them out. But, some do. I personally wonder if BK would have been capable of rape, even without KG in the room. I find it plausible that (as others have said throughout the past year of this case) he then substituted knife attack for actual sex, angry and furious about his own bizarre and hateful "sexuality." He may have come prepared for both, and been furious and disappointed that he could not, even with his fantasy enacted, achieve what he wished. Whether he was born with defects in his brain that made him this way or he created the brain/mind he had through his own learning and actions, we'll never know. It's probably both.
While researching this brain topic, yet again, I found information new to me (not all that surprising, but still, new to me). It involves the changes in the right-pre-frontal cortex (crucial in decision-making, especially the use of morals and the sense of right/wrong) in opiate addicts.
At any rate, the literature on the connection between that area of the brain and the amygdala part of the brain (basically in the brain's under-carriage), is now vast. And dysregulation (either through one's own cognition, through poor nutrition, through under hydration, through use of drugs - on and on) is commonly noted in many different aberrant mental states.
These structures are heavily involved in decision-making, risk assessment and impulse control. While much of the research is about brains with various mental health diagnoses, there's a lot more research about "normals" in various activities and simulated decision-making (a lot of these simulations are a lot like video games; which does make me and others wonder about pro-risk training of these structures in contemporary American life).
The findings include the fact that a situation (outside the brain) can cause increased risk-taking via changes in brain chemistry and brain
structure. Of course, internal stimulus is important (and is increasingly well-studied). Poor impulse control and high tolerance for risk go hand in hand, and are associated with a very large number of mental health issues (mania, schizophrenia, schizotypal. anxiety, ADHD, danger-seeking/tolerance, antisocial and on and on). Antisocial/sociopathic behavior is the best-studied, IMO - but it led many people to think that "antisocial" was the main result of pre-frontal/amygdala dysfunction, but now it appears to be just one subtype of people whose right pre-frontal cortex is compromised in some way.
No one knows how long the dysfunctions caused by opiate abuse last in the brain, to what degree these changes delay maturation/adult decision-making, etc, etc.
All of this is my own
speculation, based on thinking about this case, brain research and BK's brain, always wishing we knew more about the causes of aberrant behavior.
Frankly, even though we know a lot (and could do a kind of screening), the social implications and how this screening could ever be done society-wide/legally in the US is the hardest part - as I'm sure you are all well aware.
