WARSAW, Poland — Warsaw’s mayor Saturday unveiled a monument to a World War II hero who volunteered to go to the Auschwitz death camp and informed firsthand on atrocities there but later was killed by the communist regime.

The stone-and-metal memorial for Capt. Witold Pilecki is located near the place where in September 1940 the clandestine army fighter let himself be caught by the occupying Nazi Germans.

It was a step toward becoming an inmate of Auschwitz, which the Germans operated in southern Poland.

Pilecki’s son and daughter and other descendants joined hundreds of Warsaw residents and authorities at Saturday’s ceremony.

Deputy Prime Minister Mateusz Morawiecki said Pilecki was twice victorious, first when he was ready to sacrifice his life in defense of Poland and second when the memory of him and other resistance fighters survived the communist regime.

Pilecki wrote and smuggled out secret reports from Auschwitz to his superiors before fleeing in 1943. As a freedom fighter, he was caught and executed by the communist government imposed on Poland after the war.

His body was dumped in a mass grave and his name was taboo, as the regime wanted to erase the memories of freedom fighters. Historians are still looking for Pilecki’s remains.

Democratic Poland is making efforts to fill in such blank pages from the nation’s past with ceremonies honoring wartime and anti-communist heroes.