There is a difference between who may or may not be responsible for certain things and your solution advocating denial of rights for everybody based on a standard you can't even define.Lets see the guy who did the Colorado shooting was a hardcore OWS type and into the anarchist movement. That is not a conservative (right wing).
If we go through all those who have been involved in shootings lately, lots of ties to various leftwing causes.
Assuming that there is truth to your claim that the responsible parties of these violent acts are largely coming from one side of the political spectrum, you should be asking yourself why this is so. Lefties aren't the only ones with mental problems. So either this is a back door attempt to lock up political opponents based on convenient trends or you are missing the causal variable for the disparity in outcomes.