The most difficult work a journalist can take on is an emotional autopsy of a tragedy. The breadth of the Columbine horror and its damage on the psyches of a community and nation makes this a torturous assignment. But the emotional truths, in many ways, are just as important to expose as the reality of the horror inside the building and the failures of police; in fact, they elevate our understanding of those horrific details.

The fact that Dave was willing to spend years plumbing the minds and souls of the victims, survivors and killers is a tribute to his emotional stamina and courage. You don't follow in the footsteps of principal Frank DeAngelis where he spots a speck of blood from his best friend on the school room floor, or imagine yourself over and over under the table with student Cassie Bernall without carrying away a lot of pain. You don't immerse yourself in the diary of a killer without testing the limits of your empathy - not to mention inviting criticism from the public for the mere effort.

These are hard exercises, exercises most journalists don't dare undertake.

As a reporter, I recognize much in Dave's work that can teach us about chronicling the messy truths behind mass tragedy so we take away some insight. No, there is no sense to be made out of the senseless, but there is meaning to be found in how we react to these crimes - whether we're the police, the reporters, the local church congregations, the students who survived, the parents' of the dead, the parents of the killers. Did the parents of Dylan and Eric need to suffer such viciousness and alienation from their own community? Did the police need to hide so much information? Do parents of the innocent need to distort the truth to survive the aftermath?

He also shows us that there are important scientific and psychological clues left behind that one day may help prevent such tragedies. Yes, as a whole, they can't be assembled into any reasonable portrait for detection purposes. But we now know that they each were afflicted with mental illnesses. They were not victims of Marilyn Manson. We now know Dylan was a complicated depressive who latched on to a charismatic psychopath. We also know that Dylan expressed love.

Yes, in some ways he was like us. It's a dangerous conclusion to reach in the face of one segment of the public's earnest desire to cast him as merely evil. This is one important lesson Cullen delivers to journalists and the public: If we discover a piece of the universal - or ourselves - in what we loathe, ultimately, we might be driven harder to seek answers beyond the collective superficial views.