Columbine anniversary: guns are still the problem behind mass shootings - Vox
https://www.vox.com/2019/4/19/18412627/columbine-anniversary-gun-control-mass-shootingsHalf a decade has passed since the deadliest mass shooting in modern US history. To this day no motives in the shooter have been discovered. : UnresolvedMysteries
https://www.reddit.com/r/UnresolvedMysteries/comments/xu9sdj/half_a_decade_has_passed_since_the_deadliest_mass/