On 19 October 1943, five days after the prisoner revolt in Sobibór, Operation Reinhard was terminated by Odilo Globocnik on behalf of Himmler. The camps responsible for the killing of nearly 2,700,000 Jews were soon closed. Bełżec, Sobibór, and Treblinka were dismantled and ploughed over before spring.[94] The operation was followed by the single largest German massacre of Jews in the entire war carried out on 3 November 1943; with approximately 43,000 prisoners shot one-by-one simultaneously in three nearby locations by the Reserve Police Battalion 101 hand-in-hand with the Trawniki men from Ukraine.[95] Auschwitz alone had enough capacity to fulfill the Nazis' remaining extermination needs.[79]
During his time at Auschwitz, Josef Mengele was not the only physician there. It is popularly believed that he was the highest-ranking physician at the camp. This is not the case. That “distinction” belonged to SS captain Dr. Eduard Wirths. Wirths’ position as garrison physician made him responsible in all medical matters for the entire camp complex.
By the end of 1934 Hitler was in absolute control of Germany, and his campaign against the Jews in full swing. The Nazis claimed the Jews corrupted pure German culture with their "foreign" and "mongrel" influence. They portrayed the Jews as evil and cowardly, and Germans as hardworking, courageous, and honest. The Jews, the Nazis claimed, who were heavily represented in finance, commerce, the press, literature, theater, and the arts, had weakened Germany's economy and culture. The massive government-supported propaganda machine created a racial anti-Semitism, which was different from the long­standing anti-Semitic tradition of the Christian churches.
But they were gradually shut out of German society by the Nazis through a never-ending series of laws and decrees, culminating in the Nuremberg Laws of 1935 which deprived them of their German citizenship and forbade intermarriage with non-Jews. They were removed from schools, banned from the professions, excluded from military service, and were even forbidden to share a park bench with a non-Jew.
Approximately a half million Gypsies (a dark-skinned, Caucasian ethnic group targeted by the Nazis) were murdered out of approximately 1.6 million who were living in Europe. The Gypsies in Germany and the occupied territories of the German War machine were subjected to many of the same persecutions as the Jews: restrictive, discriminatory laws, isolation and internment, and mass executions at their camp sites, in labor camps and death camps.
He acted instantly. He sent Otto Frank a copy of “In Search” and in effect offered his services as an unofficial agent to secure British and American publication, asserting his distance from any financial gain; his interest, he said, was purely “one of sympathy.” He saw in the diary the possibility of “a very touching play or film,” and asked Frank’s permission to explore the idea. Frank at first avoided reading Levin’s book, saturated as it was in passions and commitments so foreign to his own susceptibilities. He was not unfamiliar with Levin’s preoccupations; he had seen and liked one of his films. He encouraged Levin to go ahead—though a dramatization, he observed, would perforce “be rather different from the real contents” of the diary. Hardly so, Levin protested: no compromise would be needed; all the diarist’s thoughts could be preserved.
Bartoszewski was a founder of the Polish resistance who organized an underground organization, comprised mostly of Catholics, to help save Jews. He worked to provide false documents to Jews living outside the Warsaw ghetto. In the fall of 1942, he helped found an organization (Council for Aid to Jews) which successfully saved many Jews from the gas chambers. Bartoszweski was actually imprisoned in the Auschwitz Concentration Camp between 1940 and 1941, and after his release was secured by the Red Cross he reported on the camp.

Perhaps Miep Gies, the woman who sheltered Anne Frank and her family, explained the actions of Righteous Gentiles best. “My decision to help Otto [Frank] was because I saw no alternative. I could foresee many sleepless nights and an unhappy life if I refused. And that was not the kind of failure I wanted for myself. Permanent remorse about failing to do your human duty, in my opinion, can be worse than losing your life.”
Hilberg, Raul (1985). The Destruction of the European Jews: The Revised and Definitive Edition. New York: Holmes and Meier. ISBN 0-8419-0832-X – via Archive.org search inside. The deportations ... were the work of a much larger apparatus that had to deal with a host of constraints and requirements. The effort, as we shall see, was deemed necessary to accomplish the Final Solution on a European-wide scale.[p.273] 
The first killing center set up in occupied Polish lands was the camp at Chełmno on the Ner; Jews brought in from the ghettos in the Wartheland were being killed there from December 1941. Three more camps, somewhat larger, were opened at Bełżec, Sobibor, and Treblinka (in what was known as “Aktion Reinhard”) somewhat later, between March and July 1942.
Despite the overwhelming odds, individual rescues sometimes succeeded, especially if the Jewish fugitives could pass as natives in language, manner, and appearance; if the hideout was skillfully camouflouged; if the local population was sympathetic; if geography and distance from neighboring homes aided concealment; and if organized groups or sympathetic friends provided additional safe houses and forged ration papers for essentials like food and clothing.
Several scholars have suggested that the Final Solution began in the newly formed district of Bezirk Bialystok.[48] The German army took over Białystok within days. On Friday, 27 June 1941, the Reserve Police Battalion 309 arrived in the city and set the Great Synagogue on fire with hundreds of Jewish men locked inside.[49] The burning of the synagogue was followed by a frenzy of killings both inside the homes around the Jewish neighbourhood of Chanajki, and in the city park, lasting until night time.[50] The next day, some 30 wagons of dead bodies were taken to mass graves. As noted by Browning, the killings were led by a commander "who correctly intuited and anticipated the wishes of his Führer" without direct orders.[49] For reasons unknown, the number of victims in the official report by Major Weis was cut in half.[50] The next mass shooting of Polish Jews within the newly formed Reichskommissariat Ostland took place in two days of 5–7 August in occupied Pińsk, where over 12,000 Jews died at the hands of Waffen SS,[51] not the Einsatzgruppen.[41] An additional 17,000 Jews perished there in a ghetto uprising crushed a year later with the aid of Belarusian Auxiliary Police.[52]
Mengele became interested in using twins for medical research through his mentor, Verschuer. Verschuer himself was famous for experimenting with identical and fraternal twins in order to trace the genetic origins of various diseases. During the 1930s, twin research was seen as an ideal tool in weighing the factors of human heredity and environment. Mengele and his mentor had performed a number of legitimate research protocols using twins as test subjects throughout the 1930s. Now, at Auschwitz, with full license to maim or kill his subjects, Mengele performed a broad range of agonizing and often lethal experiments with Jewish and Roma (Gypsy) twins, most of them children.
Additional barriers stemmed from antisemitism, which was rampant in the cultural climate of Eastern Europe. Gentile rescuers thus often feared censure from their fellow citizens. Moreover, significant numbers of gentiles had to confront their own personal, sometimes unconscious, anti-Jewish feelings. Indeed, postwar interviews with rescuers have shown that although they tended to describe the Jews they saved as fine people, many characterized Jews in general as dirty, loud, greedy, aggressive, dishonest, deceitful, or underhanded.
By the end of December 1941, before the Wannsee Conference, over 439,800 Jewish people had been murdered, and the Final Solution policy in the east became common knowledge within the SS.[44] Entire regions were reported "free of Jews" by the Einsatzgruppen. Addressing his district governors in the General Government on 16 December 1941, Governor-General Hans Frank said: "But what will happen to the Jews? Do you believe they will be lodged in settlements in Ostland? In Berlin, we were told: why all this trouble; we cannot use them in the Ostland or the Reichskommissariat either; liquidate them yourselves!"[45] Two days later, Himmler recorded the outcome of his discussion with Hitler. The result was: "als Partisanen auszurotten" ("exterminate them as partisans").[46] Israeli historian Yehuda Bauer wrote that the remark is probably as close as historians will ever get to a definitive order from Hitler for the genocide carried out during the Holocaust.[46] Within two years, the total number of shooting victims in the east had risen to between 618,000 and 800,000 Jews.[44][47]
Like the network of concentration camps that followed, becoming the killing grounds of the Holocaust, Dachau was under the control of Heinrich Himmler, head of the elite Nazi guard, the Schutzstaffel (SS), and later chief of the German police. By July 1933, German concentration camps (Konzentrationslager in German, or KZ) held some 27,000 people in “protective custody.” Huge Nazi rallies and symbolic acts such as the public burning of books by Jews, Communists, liberals and foreigners helped drive home the desired message of party strength.

“Awesome as they are, therefore, numbers do not in themselves prescribe the singularity of the Holocaust. But they provide a clue. For the proportion of European Jews killed during the Second World War, with roughly one of every three civilian deaths in Europe being that of a Jew, was undoubtedly greater than that of any other people, because of the Nazis’ policy toward them. Unlike the case with any other group, and unlike the massacres before or since, every single one of the millions of targeted Jews was to be murdered. Eradication was to be total. In principle, no Jew was to escape. In this important respect, the Nazis’ assault upon Jewry differed from the campaigns against other peoples and groups; Gypsies, Jehovah’s Witnesses, homosexuals, Poles, Ukrainians, and so on. Assaults on these people could indeed be murderous; their victims number in the millions, and their ashes mingle with those of the Jews of Auschwitz and many other camps across Europe. But Nazi ideology did not require their total disappearance. In this respect, the fate of the Jews was unique.”

A person who is recognized as Righteous for having taken risks to help Jews during the Holocaust is awarded a medal in their name, a certificate of honor, and the privilege of having the name added to those on the Wall of Honor in the Garden of the Righteous at Yad Vashem in Jerusalem (the last is in lieu of a tree planting, which was discontinued for lack of space). The awards are distributed to the rescuers or their next-of-kin during ceremonies in Israel, or in their countries of residence through the offices of Israel's diplomatic representatives. These ceremonies are attended by local government representatives and are given wide media coverage.

Twins were subjected to weekly examinations and measurements of their physical attributes by Mengele or one of his assistants.[49] The experiments he performed on twins included unnecessary amputation of limbs, intentionally infecting one twin with typhus or some other disease, and transfusing the blood of one twin into the other. Many of the victims died while undergoing these procedures,[50] and those who survived the experiments were sometimes killed and their bodies dissected once Mengele had no further use for them.[51] Nyiszli recalled one occasion on which Mengele personally killed fourteen twins in one night by injecting their hearts with chloroform.[31] If one twin died from disease, he would kill the other twin to allow comparative post-mortem reports to be produced for research purposes.[52]