Columbine also sparked renewed fears about the exposure of children to violence in video games, television and films — not unlike the speculation now percolating through the Internet about whether the bullets in Aurora, which fired on moviegoers just as a shootout broke out on screen, could have been in part caused by fictional portrayals of violence. Then as now, violence rekindled the debate over gun control laws.
The question of what effects such exposure might have on children remains controversial, said Ochberg, a former associate director of the National Institute for Mental Health, but it is clear that acts of violence such as the Columbine and Aurora shootings have their roots in mental disturbance. On-screen violence probably has its greatest effect on what method killers choose, he said.
As details about Holmes begin to emerge, Cullen said it is important not to rush to judgment about his motives, as he said was widely done in Columbine's aftermath. Assumptions that the teenagers were driven to murder by bullying have been largely discredited, in part because of Cullen's book.
It would be a mistake, Lanning said, to look for a "reason" for the Columbine or Aurora tragedies.
"As if there could be a reason you go to a movie theater and shoot 60 people," he said.