After a yearlong trial in Serbia 's special court in Belgrade , a judge found Rade Markovic , the chief of the secret service under Mr. Milosevic , and the commander , Milorad Lukovic , better known by his nom de guerre , Legia -- or legionnaire , for his service in the French Foreign Legion -- guilty of planning and carrying out the assassination of Ivan Stambolic , a former president of Serbia , in August 2000 .