The Nazis got some of their best inspiration from America's treatment of black people. I don't exactly think America is a shining beacon of responsibility, especially in the 1940s. I don't think America should have a death penalty, because I don't trust the American government to wield that power responsibly. If political enemies like Hitler can be executed, then political enemies like Edward Snowden are at risk too.
As an anarchist, I want to limit the power of the state because I don't trust anyone with that much power. And I especially don't trust the likes of Harry Truman and Richard Nixon.