I think everyone knew that Israel had hit squads and used them to track down and kill old Nazi SS personnel. The assination of those involved in the Munich Olympics was organised by Mossad. The ICC was in its infancy, this was their only recource.
However, this sort of brazen murder on foreign soil has gone unpunished - the expelling of a diplomat is hardly devastating. Look what the UK did when the Libyans killed PC Fletcher - they lobbied hard and the whole country was put under intense pressure for decades.
US lobby groups yield enormous pressure; so much so that Israel can get away with state organised murder on foreign soil.