While living in post-war Poland, Klingberg met Adjia Eisman, who went by the name Wanda Yashinskaya. A microbiologist by profession, she was a survivor of the Warsaw Ghetto. She had escaped and managed to survive the war due to her Aryan appearance. They married, and in 1946, they decided to emigrate to the West. They moved to Sweden shortly afterward, where their daughter Sylvia was born in 1947. It is believed that Klingberg first came into contact with Soviet intelligence while living in Sweden.