Albretch Glitz

Espionage incurs important costs yet there is little quantitative evidence on how secret services and spies work, and under what conditions they perform well. We study this question using declassified archival data from one of the most prolific secret services worldwide, the East German Stasi during the Cold War. We analyze a unique database that contains information on all the pieces of information that spies in the West sent to East Germany between 1970 and 1989. We match a subset of spies to their West German social security records, allowing us to track their careers in the secret service and in the firms they were spying on simultaneously. Analyzing the quantity and quality of information delivered, we disentangle the roles that spy heterogeneity, learning-by-doing, and career progression in the espionage object play for spy performance. Finally, we discuss the implications for counter-espionage efforts today.