Why are they talking about exile for a murderer like Colonel Gadhafi?

Early in his term as dictator, he contracted for the murder of Libyans, some of them who were living in sovereign foreign countries. He has arranged for the murder of Americans and other nationals by various means including blowing up an airplane, and a nightclub.
Rather than run the risk that his own military might hesitate to kill Libyans, he hired African mercenaries to do the dirty work. Which they did.
Why exile? Why not trial?