Well personally I don't want him to die either.
Killing him won't solve the questions Tamil people have in their minds all over the world.
Killing him will only create more hatred and then another Prabhakaran will rise after sometime.
GOSL should keep him alive and broadcast several interviews with him like they did with Daya Master and George.
Then the international community will have no option but to accept it.
Then a proper court of law should punish him for his crimes. After completing his sentence in Sri Lanka, he can be given to India to punish him according to their jurisdiction for killing Rajiv Gandhi. (But not sure whether the bugger will live that long

)