Changes in Espionage by Americans: 1947-2007

Since 1987, the Defense Personnel Security Research Center (PERSEREC) has maintained a database on espionage by American citizens based largely on open sources, and has collected files on each of the 173 individuals in the database. Although its main focus is the personnel security system, PERSEREC monitors and analyzes espionage by Americans in order to improve understanding of this betrayal of trust by a small minority of citizens. This report is the third in a series of technical reports on espionage based on the PERSEREC Espionage Database, files of information from the press, and scholarship on espionage. The focus of this report is on changes and trends in espionage by Americans since 1990, compared with two earlier periods during the Cold War. Its subjects are American citizens. Individuals are compared across three groups based on when they began espionage activities. The three groups are defined as between 1947 and 1979, 1980 and 1989, and 1990 and 2007.