I believe that we just borrow our lives from God. And He is the only one who have right to take them away from us.
It is easy to reject the idea of death penalty when we initially think that it means taking someone else's life. But, when you are in the situation where someone did an inhumane and brutal thing to one of your family members, I doubt that you would still have the same answer or belief, so it is definitely a "Yes" for me.