Historian, Phd, works at the Institute of Political Studies of the Polish Academy of Sciences and the Polin Museum of the History of Polish Jews. Studied mathematics, history and law at Warsaw University, alumnus of the Graduate School for Social Research of the Institute of Philosophy and Sociology of the Polish Academy of Sciences. Research interests: recent Polish history, the communist system, transitional justice, Polish-Soviet relations, Polish-Jewish relations and the Holocaust. In the years 2000–2016, worked at the Institute of National Remembrance. Scholar of the Foundation for Polish Science, Woodrow Wilson International Center for Scholars in Washington, D.C. And the Imre Kertesz Kolleg at Jena. Author of: Odrodzenie harcerstwa w 1956 roku (2006), Wokół Jedwabnego (2002, co-author with Paweł Machcewicz), Sprawa Henryka Hollanda (2006), Czekiści. Organy bezpieczeństwa w europejskich krajach bloku sowieckiego 1944– 1944(1989, co-editor with Łukasz Kamiński). Editor of the four volumes of the series Dokumenty do Dziejów PRL and a number of anthologies. Winner of the Polityka weekly Jan Józef Lipski Historical Award