Complex sentence: Until January 1945, Müller worked as a prisoner in the Sonderkommando and he was evacuated from Auschwitz, and freed in May 1945 in the subcamp, Gunskirchen, of the concentration camp Mauthausen.
Split into simpler sentences: Until January 1945, Müller worked as a prisoner in the Sonderkommando and was liberated in May 1945. He was evacuated from Auschwitz, and freed in May 1945 in the subcamp Gunskirchen concentration camp Mauthausen.