Paczynski was known simply as prisoner 121. He survived because he was ordered to work as personal barber to the SS commandant, Rudolf Hoess.
"The first time I was taken into his villa, I was so afraid that my hands shook and I had spots before my eyes," he said. "He came in and I cut his hair. He didn't say a word. I must have done a good job because I was called back time and again."
One day Paczynski climbed on top of a large building next to the gas chambers, removed a roof tile and peered below. From there, he watched hundreds being ordered to strip naked and guards herding them into the gas chambers: "The door slammed shut - there were loud screams, but they got less and less until there were whimpers and then just silence ... in Auschwitz you got used to anything."
Tadeusz Smreczynski, now 91, says his day "is wrecked " if he hears anything from the opera Tosca on the radio. It reminds him of the afternoon in Auschwitz when he heard the strains of an aria from the opera emerging from a camp barrack room.
"The SS just went in and shot him - just for singing. He was the star tenor in the Brussels opera. His entire family had been gassed that morning."
Smreczynski still sees ditches in the camp piled high with burning bodies during the Nazi attempt in 1944 to exterminate all Hungarian Jews who had arrived en masse.
"The crematorium couldn't keep up, so they burned bodies in the open."
Like Paczynski he survived by the luck of securing a privileged position - kitchen work which kept him from the brutal outside labour that would almost certainly have killed him.