Polish President Andrzej Duda and government ministers have taken part in the state burial of a World War II resistance commander and communist regime victim whose remains were found in a hidden mass grave.

Sunday's funeral at a Warsaw military cemetery is part of democratic Poland's efforts to face its pasts, including taboo events under decades of communism. The current conservative government is specially focused on honoring independence fighters who were imprisoned, executed and secretly dumped in unmarked mass graves by the communist regime in the 1940s and '50s.

One of them was Zygmunt Szendzielarz, codename "Lupaszka," executed in 1951. Historians found his remains in 2013 among dozens of others, and he was identified through DNA tests.