Andrzej Munk is recollected by Anna Ciepielewska, who played the role of Marta in The Passenger:
“Sometimes he made me cry and even starved me so I could feel what hunger is, but he could be also caring on the set.”

Source
www.fakt.pl

The origins of the script of The Passenger
As in the case of most of works of literature concerning the camp reality, the inspiration for The Passenger was the personal experience of the author, who had been imprisoned in Auschwitz for three years, up to the camp’s liberation.
Zofia Posmysz recollects that in the fifties of the previous century she carefully kept trace of the fate of former members of the SS, especially those from the Auschwitz camp. Even then she wondered what she would have done if she ever had met a former overseer or, for example, had been called as a witness in a trial of one of them.
She was also curious what people whom she remembered from the camp thought about their own past and about themselves in that situation so many years after the war.
However, the direct stimulus to write the first version of the radio play was a brief encounter with a group of Germans, one of whom was a woman whose voice was almost identical as the voice of Posmysz’s overseer in Auschwitz. Even though it was not the same person, the shock was extreme.
However, it also gave rise to the idea of creating a work that would show emotions and inner dilemmas of a former SS woman who is forced to re-evaluate her own past almost fifteen years after the war.
Zofia Posmysz was from the very beginning interested first of all in the present-day conflict, in showing how then, after years of peace, an SS woman could perceive herself and her own part in the structures of the death camp.

Source
www.demusica.pl
Paulina Kwiatkowska, Od słowa do obrazy, czyli
o powstaniu filmu Pasażerka Andrzeja Munka,
Muzykalia III, Conference papers 3