Mass Murders and Shooting Sprees in USA

There's a thought-provoking piece on the Mother Jones web site. It includes a map, a portion of which is depicted below:

The original map image depicts the entire nation, and further, if you hover your mouse over the various dots, a pop-up provides additional information about each incident.
I urge you to visit the original article and map:
Mass Murders and Shooting Sprees in the USA.
If Friday's horrific incident is not enough to provoke some serious debate about gun-control in the United States, it's difficult to say what is.
The irony of the situation is that statistically speaking, violent crime has never been lower in the United States. People have never been safer than now. Unfortunately, they do not feel safe, and therefore they feel the need to possess arms -- in case something like this happens to them. The facts, however, speak otherwise. In all these violent incidents, there has been only one occurrence in which a bystander shot the assailant. And even in this case, the facts bear closer scrutiny. What actually happened was this: the assailant escaped the scene on a bicycle; the citizen chased him with his car, knocked him down, and then departed his vehicle and shot the perpetrator. In sum, this is hardly a justification for his possession of the weapon; the vehicle was more than enough.
The standard (one might almost say knee-jerk) justification for the right of an American citizen to possess an assault weapon is the Second Amendment. But even this occurs in more than one version (one version was passed by Congress, another was ratified by the States and authenticated by Thomas Jefferson, Secretary of State). The differences are minimal, having to do with capitalization of certain words, but they do have one thing in common: they are almost always cited in part and/or out of context. Here is the version that Jefferson authenticated:
A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
One might first of all point out that this "right" should be understood in the context of a militia. That would have been my own interpretation. However, in 2008 the United States Supreme Court ruled (District of Columbia v Heller 554 US 570) that the right to keep and bear arms does not depend upon one's membership in a militia, and that the right extends to the use of said firearm for lawful purposes, including defense of one's home.
President Obama has sworn "to do everything in my power to prevent these senseless acts from ever occurring again." The real question, I suppose, is How much power does he have?
As David Frum, well-known conservative thinker and former presidential speechwriter, phrased it, "The real problem is to keep the most dangerous weapons out of the hands of the most dangerous people." Mr. Frum is perhaps being realistic. A general ban on firearms in the United States is simply a non-starter; perhaps he is right to begin with a ban on automatic and even semi-automatic weapons.
Such a ban would demand the surrender of all such weapons to law enforcement agencies, and further that anyone found in possession of such a weapon be subject to an automatic term in prison.
I would also argue for the imprinting of all firearms with a non-removable identification number, which shall appear on every bill of sale of said weapon. This would enable the tracking of each and every weapon from the factory in which it was manufactured through all its middle-men, all the way to the household cabinet in which it ultimately is stored. Obviously, this will do nothing about all the millions of weapons already in the hands of the public, but it is a start.