One year ago today, James Holmes opened fire at the midnight premiere of The Dark Knight Rises in Aurora, Colorado, killing 12 and injuring dozens more. Later that day, Mother Jones senior editor Mark Follman and I began working on a database of similar public shootings over the past 30 years to see what patterns we might find. But little did we know at the time that another shooter had been collecting similar data in preparation for an abhorrent crime that would relaunch in earnest a national debate on gun culture and permissive gun laws.
Researching and writing about mass shooters for months on end became pretty grim, to the point that I started dreaming about gunmen hunting me down near my apartment. It got especially strange, though, after more details of the Sandy Hook Elementary shooting last December in Newtown, Connecticut, began to emerge.