Against my better judgement, let me ask you this.

What makes you say they are protected in jail? Because they get to be alive?

Have you seen how people in jail are being treated? (At least in America)

Is it not better for them to be kept alive so they can regret their actions, rather than ending their existence? Giving them opportunity to pay for their actions with something else than their lives?

Also, why should we not attack the underlying problem of why people commit these atrocious actions to begin with? Do you really believe they were born with the intention of committing these crimes?

If you are willing to live with yourself after murdering another human being, you are no different from the rapists who are willing to live with themselves after damaging another human being for life. They might be evil human beings, but they are still human.