Let's not drag this topic to left vs right/ democrats vs republicans. Those topics rarely end without useless flaming, and aren't really what the point of this topic was. There are already too many threads like that here.
As I already stated earlier, almost the entire West has an issue with criminality. And the crimes are getting more severe, look at the Germany Christmas attack, or the woman getting burned alive on a New York subway. We can't keep building new prisons, something else has to change. A lot of countries also have community service, house arrest or other forms of punishment, which do not seem to work.
So what are the other solutions? Those called racist or inhumane, Deportations and death penalty. And sure, those wouldn't fix the problem entirely, but it would go a long way.
There are about 2 million prisoners in the US, and about 200.000 serving life sentences. In 2016, those numbers were just 1.4 million. It's going up fast, and a lot of European countries see this evolution.
So we can either let this spin out of control, or try a harsher approach. If you know the death penalty is a possible punishment, and you still commit murder, you deserve what you get.