They are among the longest unsolved murders in Germany: Up until the fall of the Berlin Wall, around 30 opponents of the Yugoslav regime were killed in the Federal Republic. Most of them were exiled Croats. The assassination orders came from Belgrade. For years, German investigators searched for the murderers and the people behind them. One of the masterminds was Josip Perkovic. German prosecutors believe the former high-level intelligence agent was responsible for the murder of Stjepan Djurekovic over 30 years ago. Now Perkovic has been indicted in Munich. Philipp Grüll and Frank Hofmann have been looking into this and many other cases. The result is a documentary as exciting as a thriller by John le Carré.