Parents don't say that - but they do forgive their child and send them to their room, or put them in time out, or any number of punishments.
Forgiveness does not require that there be no restitution. Even in the Old Testament, there was a process laid out to restore what had been taken, or damaged that allowed for the individual to remain part of the community. For example, If something was stolen, it had to be repaid 7 times as much.
the individual was forgiven, and there were consequences.
You are referring to an event that happened in a modern, western world. And the consequences for this type of action have been established in law by the citizens. A jury of his peers found him guilty, and he was ordered to pay for the murders he committed with his life.
What would you prefer the outcome to be?