It’s 25 years since Columbine. This is why I can’t leave the story behind

On 20 April 1999, Eric Harris and Dylan Klebold drove to Columbine High School in Colorado and murdered 12 students and one teacher, injuring 21 others. I was one of the first reporters on the scene, and spent 10 years writing Columbine, an examination of the massacre. This preface for a new edition marks the 25th anniversary of the shooting

How could I have known I was writing an origin story? Mass shootings didn't start at Columbine High School, but the Mass Shooter Era did. The killers' audacious plan and misread motives multiplied the stakes and inspired wave after wave of emulation. I've tried to leave this story so many times, but a diagram I have created of Columbine-inspired attacks torments me, ruthlessly expanding like an unstoppable spider web, devouring all the lives and futures in its path. It demands we address the cause. More than fifty ensuing shooters have taken nearly three hundred lives and wounded over five hundred more, and every shooter on that page left evidence they were inspired or influenced by the attack at the centre. And a 2015 investigation of Columbine copycats by Mother Jones found more than two thwarted attacks for each one that succeeded. It identified fourteen plotters targeting Columbine's anniversary, and thirteen striving to top its body count. Surviving mass shooters have admitted they are now competing with each other. Twenty-five years later, Columbine haunts our present and our future, with no end in sight.

The connections keep multiplying, and all roads lead back to Columbine. The Arapahoe High gunman studied the Columbine and Sandy Hook attacks; the Sandy Hook shooter researched the Northern Illinois University (NIU) shooting and was obsessed with Columbine; the NIU killer studied Columbine and Virginia Tech, where the shooter described wanting to repeat Columbine" and idolised its martyrs". Five generations of fallout, and they're all re-enacting the legend that set it in motion.