Time travel has not yet been invented. But thirty years from now, it will have been. It will be instantly outlawed, used only in secret by the largest criminal organizations. It's nearly impossible to dispose of a body in the future... I'm told. Tagging techniques, whatnot. So when these criminal organizations in the future need someone gone, they use specialized assassins in our present called "loopers." And so, my employers in the future nab the target, they zap him back to me, their looper. He appears, hands tied and head sacked, and I do the necessaries. Collect my silver. So the target is vanished from the future, and I've just disposed of a body that technically does not exist. Clean.