The judicialization of international relations

Why is it that Pinochet must be pursued to his dying bed in the interests of international justice but the guy who murders hundreds get to be sent home after serving about 10 days per life? The thing seems to be to have a trial but once you have had the trial who cares about whether the guy serves his sentence. Doesn't this point to a central problem with using courts to address the challenges of international relations and human rights? Even if you do catch the guy that is "responsible" how does his sitting in a jail cell solve anything? Massive violations of human rights should be dealt with by massive applications of force to stop them at the time they are happening. And mass murder at the behest of a state leader should be treated as an act of war upon the states in which the victims reside.