It was among the longest unsolved murder series 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. Decades later Josip Perkovic and the last head of the Yugoslav secret service Zdravko Mustacwere finally taken to court in Munich. On 3 August 2016 Zdravko Mustac und Josip Perkovic were sentenced to lifelong imprisonmentfor abetting the murder of a Croatian émigré in Germany in 1983. Philipp Grüll and Frank Hofmann took a look into this and many other cases. The result is a documentary as exciting as a thriller by John le Carré.