Once again, the more that those involved speak, the worse it gets.
Supposedly behind this 'Sonderaktion 1005' we have SS Blobel in charge.
According to official historiography, Himmler, at a point in time when Auschwitz, allegedly the largest of the German 'extermination camps,' began its murderous activity, is supposed to not have had the idea yet of building crematoria for the incineration of corpses: the victims of the so-called 'bunkers' of Birkenau are supposed to have simply been buried in mass graves, which had been excavated in the 'Birkenwald' (birch forest). Himmler is supposed to have ordered the cremation of bodies in Auschwitz after his second visit there on July 17 and 18, 1942. 
As a result of this alleged Himmler order, the incineration of the bodies under the open sky is supposed to have begun on September 21, 1942.
But already in the month before his visit to Auschwitz, Himmler is supposed to have ordered the SS-Standartenführer Paul Blobel, through the Chief of the Gestapo, Heinrich Müller, to eradicate all traces of the mass graves:
"In June 1942 SS-Gruppenführer Müller, chief of the Gestapo, charged SS-Standartenführer Blobel
with removing all traces of the mass executions carried out in the east by the Einsatzgruppen. This order was considered a state secret, and Blobel was instructed to refrain from any written correspondence on the subject. The operation was given the code name 'Sonderaktion (special operation) 1005
Under these circumstances one does not comprehend, why corpses in Auschwitz were buried up until September 20, 1942, and in Treblinka up to March 1943; it is also incomprehensible, why cremations in Sobibór are supposed to have begun in the summer of 1942,  those in Belzec in the middle of December of 1942,  and those in Treblinka in March of 1943.
Or to put it differently, we understand it only too well: the witnesses of the different camps had not managed to get together to agree on an identical starting date for Himmler's decision to eradicate all traces by cremation!
Blobel allegedly stated that at Babi Yar the cremation ovens were made from Jewish tombstone from the local Jewish cemetery. Laughable. The whole deal is debunked by aerial photography at the exact time of the alleged process, and that's right, nothing of the sort is happening.
Blobel on Pit Burning:
"I myself witnessed the burning of corpses in a mass grave near Kiev, during my visit in 8/1942. This grave was about 55m [meters] long, 3m wide, and 2.5 deep. When the cover had been lifted, the bodies were covered with fuel and set on fire. It took about two days for the grave to burn down. I myself saw that the grave became red-hot right down to the ground. Afterwards the grave was filled in, and thus all traces were as good as eliminated.
"Owing to the approach of the front, it was not possible to destroy the mass graves further to the south and the east, resulting from the executions of the Einsatzgruppen."
So Blobel states that "it was not possible to destroy the mass graves further to the south and the east"...but yet there is no physical evidence...oops.
What procedure did Blobel use to successfully 'eliminate all traces' I wonder?
And where did they get all that precious fuel from? For the size of a mass grave as stated, assuming partial decay of the bodies and a 30% fill factor we are talking 25,000 gallons of gasoline or oil for the top-down cremation.
And in the NMT Case 9 protocol the prosecution charges:
"The ashes, ground to dust in a bone mill, were thrown in the vast forests around. Staf. Blobel had the order to locate all mass graves in the entire Eastern Territory and to eliminate them...The work itself was carried out by Jewish work units, which, upon finishing their particular task, were shot. Concentration camp Auschwitz had to furnish continuously Jews for this Kommando."
Those 'bone mills', I wonder what kind of machines these were. They must have ground thousands, tens of thousands of bodies within a few days. With todays equipment it takes 1/2 hour to grind the bones of one body.
And they never searched for, discovered, and excavated any of the mass grave sites.
His alleged descriptions stretch the imagination. Here again we have that strange lack of detail, I would be curious to know what inflammable material would burn out such a grave for two days at a 'steady glow'.
There are also claims of blowing up the graves with dynamite, quite bizarre. I would think that after doing that, the site would be more easily discovered than before.
While some executions took place, there was a war on, Blobel revealingly stated, when asked about executions:
Why, the executions of "agents, partisans, saboteurs, suspicious people, indulging in espionage and sabotage, and,those who were of a detrimental effect to the German Army," he stridently rejoined, "were, in my opinion, completely in accordance with the Hague Convention."
There are assertions of eliminating physical evidence, but that's shot down by aerial photos, Blobel himself, and the fact that alleged massive graves/cremation pits cannot be shown to exist.