On Dec. 1, 1997, Michael Carneal, a quiet 14 year-old freshman at Heath High School in Paducah, Ky., waited for a daily prayer session at the school to end, then opened fire on the prayer group, killing three girls and wounding five others. In doing so, Carneal joined a growing fraternity of school shooters from communities such as Pearl, Miss., Edinboro, Pa., and Jonesboro, Ark.

Carneal was an avid playerof video games like “Doom,” “Quake” and “Mortal Kombat,” three so-calledsplatter games where players navigate mazes in first-person perspectiveto shoot humans and other targets, splattering blood with each kill. Severalother school shooters, including the assailants in the recent Littleton,Colo., shooting, were similarly devoted players of such games. Carnealalso claimed that the movie “The Basketball Diaries” — particularly thescene where its star, Leonardo DiCaprio, dreams of taking a shotgun toschool and shooting classmates — inspired him to commit the murders. Apsychiatrist retained by Carneal’s defense team concluded that violentand pornographic media had had a profound effect on Carneal.