As surviving Mengele victim Alex Dekel later stated:

"Mengele ran a butcher shop - major surgeries were performed without anesthesia. Once, I witnessed a stomach operation - Mengele was removing pieces from the stomach, but without any anesthetic. Another time, it was a heart that was removed, again, without anesthesia. It was horrifying. Mengele was a doctor who became mad because of the power he was given. Nobody ever questioned him - why did this one die? Why did that one perish? The patients did not count. He professed to do what he did in the name of science, but it was a madness on his part ..."