He worked extensively with Romani children. He would bring them sweets and toys, and personally take them to the gas chamber. They would call him "Onkel (Uncle) Mengele".[33] Vera Alexander was a Jewish inmate at Auschwitz who looked after 50 sets of Romani twins:
I remember one set of twins in particular: Guido and Ina, aged about four. One day, Mengele took them away. When they returned, they were in a terrible state: they had been sewn together, back to back, like Siamese twins. Their wounds were infected and oozing pus. They screamed day and night. Then their parents—I remember the mother's name was Stella—managed to get some morphine and they killed the children in order to end their suffering.[