They didn't just prosecute him - they illegally abducted him from Australia, dragged him back to Israel, locked him in prison and threw away the key.
sometimes when they decide to kill/abduct people around the world ignoring any international laws it makes at least a bit of sense (holocaust perpetrators), sometimes a bit less...
Your comment implies he is free. He spent 18 years in prison, including more than 11 in solitary confinement, and while 'released' is apparently surveilled, subject to a lot of restrictions and forced to stay in Israel.
he shall not be able to have contacts with foreigners
his telephone and Internet use shall be monitored
he shall not enter Internet chat rooms
he shall not own cellular phones
he shall not approach or enter embassies and consulates
he shall not come within 500 meters of any international border crossing
he shall not visit any port of entry into Israel
he shall not leave Israel