Have you ever known a killer? Lived next door to one, or worked in the same office as one? I haven't, but I know people who have, and their stories all share a familiar refrain: "He seemed like such a normal guy." They always seem baffled that the person they knew -- yes, perhaps a little strange, a little isolated, but still -- could turn around and do something monstrous without neon-bright warning signals going off first. So if the line between mediocrity and murder is so thin, what pushes those killers next door over the edge?

Author and Flosser emeritus John Green has a story to tell regarding that very question, one I found so compelling I wanted to share it. (A little history: back in college I did a kind of video oral history of people's teenage experiences, and had all my friends tell me their wildest high school stories. I got a lot of great stories about pranks, sweethearts and hormonal hi-jinks, but had no idea that John would come out with such a strange and disturbing tale when he sat down in front of my camera one evening.) One caveat: the story contains, shall we say, some mature themes.

Put yourself in John's position: would you feel guilty?

Update: Here's a link to New York Times article about the killing.