He knows even now, free in Mexico, that he has taken the life of a person, which is the wrong thing to do even if the victim were not amazing and beautiful. He's a killer.
He will probably not be brought back from Mexico, but I suggest that jail time will not increase or decrease his own knowledge of his crime. If he has a conscience, which is what you seem to be claiming, it bothers him as much now as it would were he in prison.
If he had a conscience, he would not, perhaps, have committed the crime he did.
We all have to live with ourselves. I just don't want to live in a world where this guy is walking around, in or out of jail, and agree with Lawmage that the sooner he's off the planet, the better.