Tuesday, two students at a Denver high school shot and killed 12 of their fellow students and a teacher, and then committed suicide. It is reported that the student-murderers, members of a group dubbed the "Trenchcoat Mafia," were devotees of shock rocker Marilyn Manson. Two years ago, David Plotz explored the sadistic byways of the Manson subculture.

It is also a virtual certainty that pundits and behavioral experts will spend this week making facile recommendations about how to prevent the next schoolyard tragedy. One year ago, William Saletan deconstructed 11 opportunistic recommendations made in the wake of the last tragedy, in Springfield, Ore.