Sonderaktion 1005

Sonderaktion 1005 (), also called "Aktion 1005", or "Enterdungsaktion" (), began in May 1942 during World War II to hide any evidence that people had been murdered by Nazi Germany in German-occupied Poland and Soviet Union. The project, which was conducted in secrecy from 1942 to 1944, focused on concealing evidence of mass murder at the Operation Reinhard killing centres, as well as at other sites. Prisoner groups used to exhume mass graves and burn the bodies were officially called "Leichenkommandos" ("corpse units") and were part of "Sonderkommando 1005"; inmates were often put in chains to prevent them from escaping.
The project was put in place to destroy evidence of the genocide that had been committed by the Order Police battalions and "Einsatzgruppen", the German death squads who murdered millions, including more than 1 million Jews, Roma and Slavs. The "Aktion" was overseen by selected squads of the "SD" and the Order Police.
Operations.
In March 1942, Reinhard Heydrich, head of the Reich Security Main Office, placed a high-ranking SS functionary Paul Blobel in charge of the "Aktion 1005", but its start was delayed after Heydrich was assassinated in June 1942. It was after the end of June that Heinrich Müller, head of the Gestapo, finally gave Blobel his orders. While the principal aim was to erase evidence of Jewish exterminations, the "Aktion" would also include non-Jewish victims of Nazi persecution.
Blobel began his work experimenting at the Chełmno extermination camp (Kulmhof). Attempts to use incendiary bombs to destroy exhumed bodies were unsuccessful, as the weapons set fire to nearby forests. The most effective way was eventually found to be a giant pyres on iron grills. The method involved building alternating layers of corpses and firewood on railway tracks. After the pyre burned down, remaining bone fragments could be crushed by pounding with heavy dowels or in a grinding machine and then re-buried in pits. The operation officially began at Sobibór extermination camp. The "Leichenkommando" exhumed the bodies from mass graves around the camp and then burned them, and task the workers were then executed. The process then moved to Bełżec in November 1942. The Auschwitz and Majdanek camps had crematoria with furnace rooms on site to dispose of the bodies and so the "Aktion 1005" commandos were not needed there. "Surplus" corpses were burned by their own prisoners "(pictured)". 
The semi-industrial incineration of corpses at the Treblinka extermination camp began as soon as the political danger associated with the earlier burials was realised. In 1943, the 22,000 Polish victims of the Soviet Katyn massacre were discovered near Smolensk and reported to Adolf Hitler. Their remains were well preserved underground, attesting to the Soviet mass murder. By April 1943, Nazi propaganda began to draw attention of the international community to that war crime. The Katyn Commission was formed to make detailed examinations in an effort to drive a wedge between the Allies. Meanwhile, the secret orders to exhume mass graves and instead to burn the hundreds of thousands of victims came directly from the Nazi leadership in April. The corpses that had been buried at Treblinka with the use of a crawler excavator were dug up and cremated on the orders of Heinrich Himmler himself, who visited the camp in March 1943. The instructions to utilise rails as grates came from Herbert Floss, the camp's cremation expert. The bodies were placed on cremation pyres that were up to long, with rails laid across the pits on concrete blocks. They were splashed with petrol over wood and burned in one massive blaze attended by roughly 300 prisoners, who operated the pyres. In Bełżec, the round-the-clock operation lasted until March 1943. In Treblinka, it went on at full speed until the end of July.
The operation also returned to the scenes of earlier mass killings such as Babi Yar, Ponary, the Ninth Fort, as well as Bronna Góra. By 1944, with Soviet armies advancing, Wilhelm Koppe, head of the "Reichsgau Wartheland" ordered that each of the five districts of General Government territory set up its own Aktion 1005 commando to begin "cleaning" mass graves. The operations were not entirely successful, as the advancing Soviet troops reached some of the sites before they could be cleared.
Aftermath.
At the Nuremberg Trials after World War II, a deputy of Adolf Eichmann, Dieter Wisliceny, gave the following testimony on "Aktion 1005":
Blobel was sentenced to death by the US Nuremberg Military Tribunal in the Einsatzgruppen Trial. He was hanged at Landsberg Prison on June 8, 1951. Nearly 60,000 deaths are attributable to Blobel, but during his testimony at Nuremberg, he claimed that he killed only 10,000 to 15,000 people.
The prosecution at the trial of Eichmann in 1961 attempted to prove that Eichmann was Blobel's superior, but the court did not accept it. Blobel's superior was actually Heinrich Müller.