I worked alongside Dr Rudolf Vrba at the medical Research Council, Carshalton, England, he was one of only four to escape from Auschwitz.
He tells of being captured by the Nazis and standing packed in a railway coach with others for hours without water and the agony they went through on hearing the train taking on water but they got none.
When they arrived in Auschwitz they were told not to drink the water from the taps as it was contaminated and they would die if they drank it. Some found that that was the truth.
He was given a belt by a friend who was executed by the Nazis and we saw him wear this belt at the medical research council. He later gave the belt to the Holocaust museum in Israil. During lunch sometimes his mind would wander and he would no longer participate in the conversation, no wonder after what he went through.
After Auschwitz he complained constantly about those who were told of the death camp and refused to immediately bomb the railway track leading to Auschwitz and thus saving thousands from death. He was correct but the people who had ignored him did not want to hear it. As a reporter said he was his own worst enemy. He worked in cancer research in Vancouver and had cancer himself. He took the cure of his cancer into his own hands but did die. A colleague said if he had let others take control the outcome may have been different.

Rudi Vrba photographed in 1978 © Wikipedia Creative Commons

A young Rudolf Vrba. The gate at Auschwitz with the motto arbeit mact frei (work makes you free) over the gate with the railway tracks, which were not bombed soon enough, and a road in Carshalton, Surrey, England