And ? What else than murder is genocide ? Ruandas executions before the genocide didnīt prevent the genocide, meaning the death penalty has no impact on those who comitted the genocide.
*sigh* These studies are applied to domestic murder, not war crime murders. I'd think that meaning would have been clear. The Rwandan genocide occured during a civil war, and considering that during such a war the law is heavily in question it is hardly a valid case when considering domestic murders in times of peace. I doubt those who commited the genocide believed that they would be prosecuted for it as they believed they would be the winners and they would be the ones making the laws afterwards, unlike those who would commit murder during peacetimes when the government is stable.
During crimes of passion you don't generally think about it, but if you are doing a premeditated murder you generally think about the aftermath unless you're particularly stupid - why do you think people often try to hide the body or make it look like an accident? People do care about consequences, which is why a lot of people don't commit crimes that they otherwise might. Now whether the death penalty is an effective deterrent or not is up for debate, and frankly I'm not too terribly invested in it, but I can at least recognize the difference between types of situations.