What is your opinion on Capital Punishment and Why?

the man who walked into my brothers home and continued to shoot him even after he was dead is in ft. leavenworth for life. I take comfort in the fact he will not do this to anyone else due to being in prison, however with prison overcrowding I fear he might get out one day and do it to someone else he should have gotten the death penalty but it's not allowed for crimes committed on Indian land.