Who serves in a dictatorship's secret police? Recent research examines why dictators use repression. However, little is known about the inner workings of the repressive agencies that are tasked with the implementation of state terror. To fill this gap, we study the staffing of a secret police. We argue that dictators seek to maximize compliance within their key repressive agency to stay in power. To this end, regimes draw on ambitious but underachieving officers who are threatened by the military's `up-or-out' promotion system. To boost their military careers, these officers are likely to demonstrate their loyalty by zealously executing repressive orders. We test this argument using matching techniques in a micro-comparative analysis of the staffing of Battalion 601--the notorious Army intelligence unit responsible for thousands of deaths during Argentina's Dirty War (1975-1981). Original archival data on over 4,000 officers allow us to systematically study biographic differences between those who entered Battalion 601 and those who were employed in any other Army unit. We find that officers of Battalion 601 indeed consistently underperformed at the officer academy. The study contributes to our understanding of repressive state bureaucracies with important implications for (post-)conflict processes and regime stability.
