I think he should be set free. He should be given a good job. He should have a really nice place to live. He should have a beautiful wife and live in peace and happiness.
Then, once he is comfortable and complacent, he should have a homemade explosive set off without warning in close proximity to him shattering everything he holds dear and maming him. He should live just long enough after that to see his life crumple and to suffer weeks of agonizing pain. He should be transfused with pigs blood to keep him alive. And then he should be left in an alley on a cold rainy night to slowly die, alone, as rats chew on carcass.