I think that the LAPD, LASD, RSD/PD, SBPD/SO will all re evaluate their response processes; the tactics and procedures used will be reassessed, and tightened/fine tuned for any other similar situation (and that's NOT saying what they did was wrong...).
I think we can learn a ton about how mental illness hides, and how to find it. When you consider that this man had to take the MMPI and other psychological evaluations and got through them and hired into a job that involves weapons, then you also have to look at that process and how to better interpret the MMPI/other evaluation exams. Steps may be made towards a better "weed-er outer" (if that's even a phrase) during background processes.
It may teach us something about how depression works; most people who are depressed are NOT violent towards others; but they are to themselves. So did he have true depression, or was there a character flaw which, combined with depression, can alert us to a more substantial risk towards violence of others? Is there something which we can identify that might allow us to more effectively treat MI?
It may teach us something of how the public responds to the "anti-hero". How to gauge reactions from the public at large (there were people with signs, for heaven's sake, encouraging Dorner!) and how to avoid/divert this sort of thing for the future (which will also lessen risks to LE, and to the public).
It may teach LE how to better handle a domestic terrorist, or respond during a terrorist attack, in the future.
If it gives us a picture of how this criminal, evil-hearted man thought, then there may be ways to use that knowledge to further protect ourselves somehow in the future.
What made him this rage filled? What happened when he was little that made him an "injustice collector"? How did he get past the psych screenings (and while I don't know for sure, I suspect they do clearances in the military, too, for some of the jobs. Did he take one? Was he cleared? how did he manage that?)
How did a man, who was a bit of a bully, get this far and into a position of responsibility in LE and in the Navy?
Knowing more of that, we can better construct defenses against people like him for the future; we can start to see signs and symptoms of MI and may be able to better predict their actions, violent or otherwise, and be able to weed out those folks from armed positions.
There are many, many things that this man can teach us, if we get past the horror of his actions and delve into his mind a bit more. And there are things which were, in hindsight, huge screw-ups (e.g. him passing the psych evals) that may be able to be corrected for future applicants.
And on and on...many, many things we can take away and have this at least be something we learn from, so that it's NOT repeated in the future.
That, at least, is my hope...my prayer. That we take this horrific event and find value in it; it's how we can honor those who were killed...for if there are lessons to be learned, and we fail to learn them...well...
Of course, that is simply my own opinion, and as I'm not in a position to actually forensically analyze him, I'm somewhat limited in knowing what we could learn. But that there *is* something we can learn, I have no doubt at all.
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Herding Cats