Later Juozas Ambrazevičius actively participated in the anti-Nazi underground, four members of the Provisional Government were imprisoned in the Nazi concentration camps. There are allegations by certain journalists that, in 1973, a Committee of the United States Congress made conclusions that Prime Minister of the Provisional Government Juozas Ambrazevičius' and Jonas Šlepetys' were not responsible for the Holocaust in Lithuania. However, according to a subsequent clarification issued in 2019 by the Foreign Affairs Committee of the US Congress, the investigation was not conclusive and did not amount to a "rehabilitation" of Ambrazevičius/Brazaitis. The investigation into his wartime activities was discontinued after Ambrazevičius/Brazaitis passed away in 1974.