We can forgive him but that does not mean he should be walking free amongst us.
Agca did not wrong me, so there is no reason for me to forgive him. He wronged Pope Paul II, and Pope Paul II personally forgave him.
The state, on the other hand, is not a candidate for eternal life and is not in the business of forgiving anyone according to the Christian model. An effective and wisely led state seeks to ensure justice and to discourage wrongdoing by causing wrongdoers to feel adverse consequences for their misconduct. The message is sent to would-be wrongdoers reminding them that the same thing will happen to them if they persist in wrongdoing.
On that basis, this decision to release at a relatively young age a cold-blooded murderer of not just one person but two persons does not send a sufficiently strict message to would-be wrongdoers. On the contrary.