Studied history at the Humboldt University in Berlin. In 1984 he wrote a PhD thesis on Russia’s medieval history. Between 1990 to 1991 he worked for Joachim Gauck, the Federal Commissioner for the Stasi Archives, and since 2001 he has been a member of the Research Team on the SED state at the Free University in Berlin. Since 2006, he has been the scientific director of the GDR Museum in Berlin, and since 1990 he has written many publications on the history of the GDR, including Die heile Welt der Diktatur (1998, translated and published in Polish as Wspaniały świat dyktatury, 2003).