Hugo Höllenreiner lived with his parents and five siblings on Deisenhofener Straße in Munich's Giesing district. His father operated a transport business for a long while. Höllenreiner and his siblings were confronted with the common prejudices against Sinti and Roma from an early age. They were regarded as 'antisocial' and criminal like all 'gypsies' and were excluded from the National Socialist 'people's community' due to ever new regulations and laws. On March 8, 1943, Höllenreiner and his family were arrested by officers of the Munich 'Office for Gypsy Affairs' and detained at police headquarters. On March 13, 1943, he was deported to the 'gypsy camp' Auschwitz-Birkenau. He and his parents and siblings survived the concentration camp, but 36 of his relatives who were also deported were murdered or died due to the catastrophic conditions in the concentration camp. From then on, Höllenreiner endured the after-effects of the brutal medical experiments conducted by the SS physician Josef Mengele, to whom he had fallen victim to as a young child.
Hatred and prejudice against Sinti and Roma, who were now referred to as 'vagrants' by the police, continued unabated after 1945, even at school, from which Hugo was excluded by his teacher at the age of 14. Höllenreiner later moved to Waldtrudering (a district of Munich) and then to Ingolstadt. He fought in vain for a long time for appropriate reparations for the injustices he had suffered. He was unable to talk about his experiences in the camp for 50 years. Since the 1990s, however, he has been actively involved as a witness in public and in schools to preserve the memory of the Nazi genocide of the Sinti and Roma.