Honestly, as a psychology major, your dad needs to understand playing violent video games, as well as being exposed to violent media in general, is not the primary determining statistic with regard to violent crime. The one statistic that translates to the likelihood of you going out and killing someone is economic status. You heard it right: poor people are more likely to commit crime. Even so, any reasonable person could tell you just because Johnny's poor, he's not necessarily going to shoot his neighbor Jill out of the blue.
Furthermore, I found this neat article on google scholar stating leisure activities that take place away from the household show positive associations with rates of crime, whereas leisure activities in the household show negative associations with those rates.
http://www.jstor.org/pss/2579022
Honestly, your dad's a victim of political spin. Violent video games and crime is a hot button topic these days, and there are always people trying to scare you into thinking something will kill your or cause you harm. Your dad needs to calm down, understand a playing a bloody game or not is the least of his worries if he's truly concerned about your well-being, and stop listening to anyone who will tell him there's something wrong in the world today without trying it out for himself. Geez, you could be killed in a serious car accident tomorrow, and he's worried about you playing a violent game?