His application to join the Nazi Party was declined in 1939, because he had been married to a Jewish physician, Dr. Lilly Weil, with whom he had two children and from whom he had been divorced in April 1935. While the children survived the war in the UK, Lilly Pokorná as an internee in Ghetto Terezin led the first radiology station in the camp.[2] After the war, she emigrated with the children to Brazil.
During World War II, Pokorny worked as a medical officer of the German Armed Forces. Despite not being a member of the SS or the Nazi Party, Pokorny wrote to Heinrich Himmler to suggest sterilization of Russian prisoners of war utilizing the sap of the caladium plant, which, according to an article in a medical journal, was thought to cause sterilization in mice.[3][4] Pokorny suggests the forced, covert sterilization of millions of prisoners, and wrote that he was "led by the idea that the enemy must not only be conquered but destroyed" (emphasis in original) and the immense importance of this drug "in the present fight of our people."[5] He continued:
If, on the basis of this research, it were possible to produce a drug which after a relatively short time, effects an imperceptible sterilization on human beings, then we should have a new powerful weapon at our disposal. The thought alone that 3 million Bolsheviks, at present German prisoners, could be sterilized so that they could be used as laborers but be prevented from reproduction, opens the most far reaching perspectives.
This was received by Himmler with great interest, who ordered the procurement of caladium seguinum with the intention of conducting sterilization experiments on prisoners in Dachau concentration camp.[6]