They needed some place to lay blame to explain why seemingly normal, privileged young men would engage in such barbarism. The convenient culprit was violence in media. Government at all levels couldn't do enough to investigate and interrogate the entertainment industry, implying that movies, music and video games influenced these impressionable boys, whispering directions and encouragement in their ears. And a group of senators wrote the Federal Communications Commission suggesting it start using its licensing authority to police the content of programming. No one who was calling for a dispassionate analysis of the real impact of violent media on society was getting heard.
Moral panics happen here with uncomfortable frequency.
While there are all sorts of studies that claim to show an increase in aggressive behaviors and attitudes after viewing violent images, these results have not been shown to translate into an increase in violence in the long run or in real-world settings. The thesis that watching violence begets violence may seem intuitive, but falls apart on close examination. If this were the case, then everywhere brutal, gory video games are played and similarly bloody television shows aired, violence would be uniformly occurring. But that's simply not happening. Japan is notorious for its graphic entertainment yet experiences little actual violence.