Gaming is a new common medium for most people under the age of thirty. What commonly is explored in the press is when a younger person commits a crime and they happen to play video games. What isn't really explored, or even properly explained, is that tens of millions of violent games are sold every year.
How many people under the age of 30 commit a violent crime? Along with the rise in popularity in video games has been the rise of the PC and the internet. Much as the media and 'experts' like to play on the fact that the rise in violence in society has been following the rise in popularity of gaming, you could also attempt to link the rise of people using the internet and getting upset over something someone said or another such foolish thing.
Ask 1000 males between the ages of 17-30 if they have played a violent game within the last few months and the majority, overwhelming more then likely, are going to say yes. Should it really come as a surprise that a violent criminal of that age group happens to have played games?
I think if you choose to, you can 'prove' the violence relation to video game factor pretty much any way you want. It is a mass entertainment medium at this point, one that the prior generations don't tend to take part in so they tend to attribute it to differences between generations. Frequently the older generation attempts to relate GenX and younger people as being better with computers due to their playing video games on a console, as if they have any relation whatsoever. Fifty years from now when gaming is commonplace amongst all generations this argument will be over. It is a generational gap issue far more then it is a societal one.