Somehow, this possible motive doesn't make the killings any less senseless.

Speaking of senseless killing, I'm not looking forward to next month.

On April 19, 1993, following a 51-day standoff, federal agents raided the Branch Davidian compound near Waco, Texas. A fire, later determined to have been set by the Davidians, destroyed the compound and killed 57 of its residents.

On April 19, 1995, a bomb inside a rental truck exploded at the Murrah Federal Building in downtown Oklahoma City, killing 168 people in what was then the worst terrorist attack on U.S. soil.  The killer turned out to be 27-year-old Timothy McVeigh. McVeigh’s ex-Army buddy, Terry Nichols, was also charged in the crime.

On April 20, 1999, two armed highschool seniors, Dylan Klebold and Eric Harris, walked through Columbine High School in Littleton, Colo. In the end, 12 students, one teacher and the two murderers were dead.

And on April 16, 2007, a 23-year-old South Korean student killed 32 people at Virginia Tech.

The first three are all connected.  McVeigh picked the April 19 date as a symbolic protest against what had happened at Waco two years earlier.  And Kelbold and Harris picked April 20 (the first school day after the 19th) to conduct the Columbine massacre — although they had no political angle, it was their hope and desire to "outdo" McVeigh.

It doesn't appear that Sueng-Hui Cho, the Virginia Tech killer, picked his date in relation to any of the prior outrages.

Still, with next April 20 being the tenth anniversary of Columbine, who knows what some unhinged elements of our society might do.  In England, they've already thwarted one attempt to do a school bombing on April 20.

There's obviously been a lot of public programs designed to prevent another such occurence.  And that's a good thing.

But still…. if I were a high school student, I would seriously consider staying home on April 20.