Marko completed his studies in law and English at the Karl-Franzens-University in Graz with a Dr. jur. (PhD in law) and a MA in English translational sciences in 1977.

After post-graduate studies in political sciences and sociology at the University of Munich, he returned to Graz, filling the position of an assistant professor at the Faculty of Law. In 1994, Marko earned a Doctorate of Science for Austrian and Comparative Public Law, the Theory of State and Law (Allgemeine Staatslehre) and Political Sciences and became Associate Professor.

Today Marko holds a Chair for Comparative Public Law and Political Sciences at the Institute for Public Law and Political Sciences at the University, focusing on interdisciplinary studies of nationalism, ethnic conflict, power-sharing in divided societies, law and religion. He also focuses on territorial and cultural diversity governance regarding the integration of indigenous peoples and new minorities stemming from immigration.