I don't think I get your point. Is it that the more someone is left-wing, the more they are likely to be killers? And extrapolating, the more right wing people are, the less likely they are? That is a wild take.

My point is that Democrats and Republicans disagree on social policies, but on the economical side they are very close to each other. They are two shades of capitalist policies. Other countries have parties that are simply non-capitalist - that is the "left".