If video games makes one resort to commiting violent acts in the real world, odds are they were a pretty messed up and disturbed individual to begin with prior to being exposed to video games.
The way I see it, if one has mental issues that would eventually lead them to violence, it all depends on the type of match that sets them off. Could be a book, movie, music or even video games.
Just depends on the individual, and thus the blame should never be the material. Anything can be a hazard in the wrong hands, but that doesn't mean it should be banned or taken out of the hands of everyone just because it was misused by other individuals.