He hasn't served his sentence, only half of it. He's out on parole/licence.
He's been convicted by a jury.
He's shown no remorse or even understanding.
Prison is supposed to be about rehabilitation; clearly it hasn't worked here. (Curiously, the modern penal system is based on the original Magdalen Institutions—not the laundries—with work, moral improvement and transient removal from society as the aims.)
Yes, all prisoners deserve and should get rehabilitation and re-integration into society.
But first, they must accept what they have done.