On July 20, 2012, James Eagan Holmes walked into a Century movie theater in Aurora, Colorado, threw tear gas grenades and shot into the audience with multiple firearms, killing 12 people and injuring 70 others. He had colored his hair an unnatural shade and after his arrest, announced he was the Joker. The film that was showing was a midnight screening of The Dark Knight Rises. Again, it's natural to leap to easy conclusions to try to make sense out of something senseless, but there's nothing in Batman that isn't also in a dozen other places, and the perpetrators of other mass shootings didn't need a comic-book villain to justify their crimes. Police have confiscated multiple "Death Notebooks" from students grades K-12, writing down names of people they'd like to die in imitation of the manga series Death Note, where a magical notebook makes that desire a reality. But while school violence is a serious issue, there's no indication that these books are linked to actual violent intent.
T Campbell has written quite a few online comics series and selected work for Marvel, Archie and Tokyopop. His longest-running works are Fans, Penny and Aggie-- and his current project with co-writer Phil Kahn, Guilded Age.