I would like to express my point of view on this problem.
First of all, it's God who creates/gives our lives and only God has the right to take a person's life away. We, people, think that the criminal desrves the death penalty but we may be wrong/we may be mistaken.
Secondly, if a criminal committed a very serious crime and deserves the death penalty, he/she must be sentenced to life imprisonment to atone for his crime. The criminal will be given an opportunity to think over his action, to realize how sinful it was and to regret about it. We must give an opportunity to the criminal to save his soul. Besides, he will work for other peoples' benefit.