No, Jesus did not believe in capital punishment.
In fact, he was pretty strongly against it in John 8:7, when he literally interrupted and stopped an execution. What do you think a stoning was?
In Matthew 5:38–39, he explicitly sets aside strict retributive violence in favor of non-retaliation, mercy, and restorative justice.
In Matthew 26:52, Jesus literally instructs Peter NOT to kill someone, even though it would have prevented his death.
Also, Jesus frequently quoted Hosea 6:6 ("For I desire mercy, not sacrifice, and acknowledgment of God rather than burnt offerings.")
To say Jesus supported the death penalty is not supported by scripture. His teachings systematically dismantled the moral foundation of capital punishment by:
- Disqualifying the executioner due to human sinfulness (John 8).
- Revoking retributive equivalence ("an eye for an eye") in favor of mercy and non-violence (Matthew 5).
- Prioritizing time for repentance and redemption over irreversible physical destruction.