From Time:

The president of Virginia Tech, Charles Steger, should resign. But not because of the school’s rather slow realization Monday morning that a demented murderer was on campus. Mass shootings are infinitesimally rare. As the Department of Justice points out here, in 2004 less than .1% of all homicides involved five or more victims. The rate of homicides involving more than two victims has been under 1% since at least the mid-’70s (although the rate of two-victim murders — like Cho Seung-Hui’s first two killings in Ambler Johnston Hall — has increased over the years). In other words, statistically speaking, the cops who arrived at Ambler Johnston on Monday morning to find two dead bodies had every reason to believe the killer was finished. [I agree.]

But assuming that an unknown murderer won’t leave the scene and keep shooting people — something almost no murderer does — is different from assuming that a person who has long been identified as a threat, as Cho had, won’t hurt someone. The fateful decisions that cost the lives of 30 more people at Virginia Tech weren’t made on Monday morning; they were made in the previous 18 months.

[It appears to be so. If you don’t count all the myriad problematic and irresponsible decisions that were made before that, i.e., no competent professional help to this adolescent/child when he needed it anytime in his entire life history.]