I found two key takeaways:
You may not be able to predict it, but you can certainly defend against it."“I'm not sure you can even predict it,” says Mark Safarik, who retired in 2007 as a senior profiler in the FBI's famed Behavioral Analysis Unit."
A few years ago I saw a program examining the psychological issues behind why and how criminals are able to do the things they're able to do (murder, mayhem) when normal citizens don't. Essentially, there's what can best be described as a behavioral control switch in the brain which prevents ordinary humans from harming others unless their own life or limb faces immediate threat. Even then, many, perhaps even most humans will still only fight back with minimal effect even when faced with imminent death."Many other people “have all these symptoms, but they never get the disease,” Levin said. “They may blame other people for their problems. They may be isolated so they have no support systems in place. And, yet, they don't hurt anybody.""
On this forum and others, we know this as the sheep / sheepdog distinction. Most people are sheep, few are sheepdogs, and obviously, the criminals are classified as "wolves."
In criminals prone to violence, mayhem, and murder, the area of the brain which acts as the gatekeeper is usually not working quite right. It's even been measured on laced glucose uptake PET scans.
Although this phenomenon has been measured in criminals, to the best of my knowledge it hasn't been measure in mass murderers. As indicated by the article, they're clearly not in it for the money, and they're also quite rare compared to your average violent criminal or serial killer (although serial killers are nearly as rare; just not suicidal).
The big issue is that "many other people “have all these symptoms, but they never get the disease.""
Most of us are normal humans. We get depressed. We have joy, trials, and tribulations. On occasions we get depressed, and on other occasions we feel hurt, and sometimes incredibly enraged. Does that mean we flip a lid and go on a suicidal killing rampage?
Heck no! We do whatever it is we do to cope. Some of us talk to others. Some bury ourselves in movies or books. A few of us drink or use drugs. Some amp our own chemicals through sports.
What we don't do is pull a Cho, Loughton, or Hasan. If my theory is correct, those missteps are relegated to the same cranial defect present in most violent criminals. The difference between criminals, serial killers, and the "going out with a bang" nutjobs like Cho and Loughton has to do with what drives them, not what's wrong with their brains.
I think the only reason Loughton was smiling during his mug shots and arraignment is that he fully expected to die during his suicidal rampage, but he was tackled by some folks who are...
...normal. Folks who care. Folks who were ready to roll.
Maybe I'm wrong. Perhaps when the SHTF, there are a lot more people out there who "get it." During the two incidents I've encountered over the last 25 years, one in the mid-80s, the other this past summer, and out of about two dozen folks present at each incident, I was the only one who stepped up to the plate. The others just stood around watching.