Original sentence: Gas chambers were used in the  Nazi Third Reich during the 1930s as part of the so-called "public euthanasia program" aimed at eliminating physically and intellectually disabled people, and later the mentally ill
Edited sentence: However, not a single autopsied body has been shown to have been gassed.More notoriously, gas chambers were used in the  Nazi Third Reich during the 1930s as part of the so-called "public euthanasia program" aimed at eliminating physically and intellectually disabled people, and later the mentally ill.The Nazis, faced with the threat of the Red Army, decided that their time would be better spent covering up their actions instead of resting and preparing for battle