They used to actually prosecute and execute criminals?
They made an exception for Eichmann.
He was a slippery eel, smuggled into Argentina on one of President Juan Perón's "rat lines." One of the most hunted men in the world yet he traveled internationally freely. In the 1950s he brazenly went home to Germany to attend the wedding of a niece. Everybody in the city knew he was there, the city bigwigs even came by to pay their respects. But no one turned him in.
So when Israel came by credible information that Eichmann was living in Argentina, they did not dawdle. They kidnapped him and doped him and walked him onto a commercial airliner. Told the airport officials he was a drunken reveler, flying home to Israel after having a few too many while spectating a soccer match.
Remember this was in 1960, when there still were most of a hundred thousand Jews living in Israel with a Nazi tattoo on their arm. So needless to say, there was a great hue and cry from the citizens of the country that Eichmann should be summarily executed without trial because he did not deserve to be treated any better than he had treated the millions of Jews the Nazis murdered.
But the Israeli government insisted that it MUST be a public trial so the world could see that the Jews were not the same lawless animals that the Nazis had been.