Bob:

I don't like looking at the big picture in these things because I don't think there is a big picture. These are crimes committed by individuals and looking for a so called 'root cause' is a distraction from that. What motivates these criminals is irrational and their objective is evil, but the planning and execution are a perfectly rational series of decisions and actions by an individual. They decide and they decide what they can pull off. It seems to me that it is much more productive to look at these occurrences as crimes that take advantage of some obvious vulnerabilities and the most productive way to address them is to remove those vulnerabilities to the extent possible.

Beyond that the additional factor is the specific publicity given to these crimes. The world knows the name and faces of these criminals. Some of this is the result of a simple reward system. If you want everybody to know who you are, there is a surefire way to do it. The media will oblige the desire to be known. If something is rewarded, there will be more of it...so stop giving the reward.

As far as specific remedies, except for streamlining commitment procedures, I don't think there is much more than that. If you want more that is to be found in religious philosophy and perhaps the concept of original sin. People do evil.