After the establishment of the Warsaw Ghetto Maria, at the urging of friends, remained with her daughter on the Aryan side. She received documents in the name Pogonowska, which she used for the rest of her life. She repeatedly changed her residence and made her living by trading in foodstuffs, cigarettes and soap. Her older sister and parents were sent to the Warsaw Ghetto, as well as the family of her husband. Pogonowska and her daughter were in the district of Ochota during the Warsaw Uprising. They were cast out of their apartment to the labor camp in Bunzlau (Bolesławiec), which the Soviet Army liberated in February 1945. At the time, they were unaware of Mieczysław Proner's death, who was omitted in the lists of the victims of Katyń massacre, disclosed by the Germans in 1943.