We don't need the death penalty. What we need is stricter privations in place for the most heinous perpetrators; no video games, no television, no freedoms, no exceptions. We can cure this leniency without reinstating capital punishment.
The main reason I don't believe in the death penalty is because I think things like the bastard that killed those three girls should be made to suffer. Keep him in a windowless room with just enough ventilation, give him just enough bland food and water; the basics to keep him alive. Let him decay mentally and physically. I'm a firm believer in rehabilitation, but when this is an impossibility, I don't mind my taxes paying towards the worst of humanity existing in misery for the rest of their days.