NARRATOR While the Jews were the focus of the Final Solution, the Nazis had also identified a number of other enemies, including Jehovah’s Witnesses, homosexuals, Roma, Sinti, Soviet POWs, people with mental, intellectual, or physical disabilities, and political dissidents of any type. By the time the camps and killing centers were opened and established, half the victims of the Holocaust had already been killed in the East at mobile killing sites—essentially locations where massive numbers of people were murdered, usually by shooting. The shooters were often members of a specialized mobile killing squad called the Einsatzgruppen—or Operation Group. The Einsatzgruppen worked in four massive squadrons—all moving East behind the German army. Their goal was to murder with efficiency. They were expected to shoot people for up to eight hours a day, in some cases killing two people with a single bullet. One of the great puzzles of the Holocaust is what was going on in the minds of the perpetrators. The Einsatzgruppen were helped in their task by local collaborators—civilians and police. The shootings were typically done locally, publicly, and witnessed by neighbors, some of whom aided and supported the shooters by driving wagons, cooking, clerking, and digging mass graves. Their method was to march a large group of their victims out of a town, collect their valuables, remove their clothing, line them up or lay them down in a trench—sometimes dug by the victims—and shoot them. In one instance, Einsatzgruppe C massacred 33,771 Jews over two days in a ravine at Babi Yar, near Kiev. This massacre is commemorated by poet Yevgeny Yevtushenko: MALE VOICE “… And I myself am one massive, soundless scream above the thousand thousand buried here…” NARRATOR By the summer of 1941—in response to the psychological impact on the murderers— Einsatzgruppen began using gas vans as an alternative to shooting. Victims would be locked in a closed unit on the back of a truck and asphyxiated with carbon monoxide from the truck’s exhaust. This method proved more effective at killing a number of innocents simultaneously and anticipated the gas chambers that would be employed at the killing centers.