“In the winter of 1941, a Jewish gravedigger from Chelmo, the western province of Poland, appeared in Warsaw and desperately sought a meeting with Jewish leaders.
He told them the Nazis were rounding up Jews, including the old, women and children, and forcing them into what looked like tightly sealed buses. The buses had the exhaust pipes redirected into the cabins. The Jews were killed with carbon monoxide. He had helped dig the mass graves for thousands of corpses until he escaped.”