Here is a professional truth:

We carry every story, good and bad, with us. It’s the result of the empathy we need to do our journalism job fully. All the good journalists I know feel their stories to the bone despite professional detachment and analytical scrutiny.

Today is the anniversary of the Columbine shooting, the story that has followed me most intensely for a decade. I write this exactly ten years after Eric and Dylan went bowling.

First, perspective.

My career has been filled with wonderful stories. I have been overwhelmed by fascination and joy, happiness and friendship. My life has been changed for the better by most of my subjects. The good has outnumbered the bad by tenfold.

I have also seen horrors beyond Columbine. I’ve tiptoed around the bodies left by drug gangs and corrupt cops in Rio, looked into the eyes of sudden widow in India, and faced the grief of the family members of the Oklahoma City bombing. I’ve listened quietly to people tell me of personal losses and fears, and I have seen the aftermath of scores of fatal crashes and deadly fires.

That’s the job.

And though we feel all these things, you would have to add up the background pain of a hundred journalists to equal that of any of the victims of an act as senseless and violent as Columbine.

Not long after the event my colleagues at the university wisely took the opportunity to discuss stress and trauma issues among journalists. It’s a valuable discussion. But at the time it smacked of too much self pity to me. By comparison to our subjects, I felt, our pain was trivial. But trivial as it may be, I now look back on how that story changed me. I have yet more empathy for the victims in any story.

For them multiply what I experience by 100.

Or 1,000.

I felt the first blow of the story days after photographing the tortured faces of terrified parents and shell-shocked students. On my way out of a big public memorial service the weekend after the shooting I came across the first paramedic team on the scene. The small group stood under an umbrella at the back of the huge crowd — not in a place of honor as I would have hoped. There gazing blankly at the space above the stage were the men and women who held the dead, dying and injured.

Dr. Chris Colwell, center, the emergency physician who tended to the wounded and dying at Columbine High School immediately following last Tuesday's shootings, stares blankly beside paramedics as the names of the thirteen victims killed in the shootings are read at a memorial service in Littleton, Colo., Sunday, April 25, 1999. The victims were eulogized by Vice President Gore, Denver Archbishop Charles Chaput, and the Rev. Franklin Graham.

I snapped two poorly composed frames, crumpled to my knees and sobbed for five minutes. I gathered my wits and went off to develop film and send my images to New York.

I am sure that catharsis helped me get through the next months of covering the story again and again, listening to the harrowing details from survivors and steeling myself to the growing hostility from the larger community.

That hostility is another difference from all the other stories I’ve covered. Our heavy presence, rush to deadlines and competitive streaks left a foul taste in the mouths of anyone who watched it happen. Within days the surrounding community, which had no connection to the story beyond proximity, let its discomfort with our process be known.

In a few cases we deserved it. Our behavior was terrible in spots, and all it takes is one nasty action to create a rumor, a stereotype, an expectation. But all the good and sensitive journalistic behavior I saw was trumped by the bad.

Not only was this story tough in subject matter, but we had a very tense relationship with the subjects.

All these emotions well up in me at every subsequent Columbine stop — the funerals, the shot-up school tours, the exhibition of the weapons, the ticking anniversaries. It caught me this year as I heard the father of victim Rachel Scott speak about his daughter.

The reactions vary, from a jaw clenched to soreness, to sleepless nights like last night. But my expectations of subjects have also changed.

In August 2007 I was in Price, Utah, to cover the ongoing tragedy of the collapse of the Crandall Canyon Mine. My jaw clenches now whenever I imagine covering a community struck by tragedy. I wrongly anticipate excessive resistance if not outright hostility.

I walked out of my motel room on the first morning I was on the story to find a new tire flat. I looked around it and found no nails, no holes. Rather than my assumption being that a seal or a valve had broken, I instantly jumped to the completely irrational conclusion that someone in town had taken it upon themselves to go empty a few tires in the lot of one of the journalist motels.

I was, of course, wrong. And, despite losing nine local miners and rescue workers, the community was no more difficult to interact with than any other.

Over all the other tragedies I’ve seen, perhaps it is because Columbine was so senseless and unexpected that it has stayed with me. Drug wars in Rio and untimely death in India can unfortunately be expected. Crashes and fires happen every day. In 1999 a school shooting in an affluent suburb with such a toll of dead and injured was not expected. Unfortunately now stories like that are just another part of the tragedy landscape.

Again, all of this reaction is trivial by comparison to the victims, or to those who have seen mountains of tragedy.

To see and hear the tales of journalists really haunted by what they have covered, watch in “Dying to Tell the Story” Don McCullin’s thousand-yard stare as he describes his war-dead subjects climbing out of his film filing cabinets at night and walking the halls of his English country home.

Or listen to Paul Watson in an interview with Fresh Air’s Terry Gross describe his inner conversations with Staff Sgt. William David Cleveland, the dead man he photographed being dragged through the streets of Mogadishu.

My point is not to show obsession with my reactions to one story. It is to make clear that no matter what stories we cover, we carry them with us forever after.