I've heard this happened (not from deniers but from mainstream historians who accept that 5-6 million were murdered, etc). Is it true and what was the broader context in which it occurred?
If it happened: Was he acting alone? What were his motives? Did any other senior Nazis figure out what he was doing? Were his attempts to stop the genocide countermanded by other SS officials?
The Holocaust was not one thing. It is a name for a series of measures taken by a large State apparatus. This included killing camps. It embraced death squads. As well as concentration camps (which may or may not have had death as an immdiate aim).
Different things ended at different times. The death squads generally ended early, (I think they were finished by 1942/42), mostly since it was a pretty inefficient way of killing*. Death camps started up in earnest around that time.
Concentration Camps, where (in theory at least) people were not supposed to be killed, continued till the end. And people continued dying throughout.
We need to remember another thing. Not everyone was killed directly. Lots of people died due to starvatrion and illness brought on by their confinement and mistreatment, not the gas chambers. Anne Frank died of Typhus for instance. Estimates that I have read range from 1/3 to nearly 1/2 of all dead went this way. Of course they are as much victims as anyone else.
Himmler's orders in late 1944 and early 1945 ended the operation of the death camps. Although people continued to die in those places of mistreatment until the end. The why is complicated. The Allies had already by that time started reaching some of the camps (the Soviets had reached one as early as July '44). The areas where the camps had been located had been rear areas and now were battlegrounds. The men there were needed desperatley for the front. In addition, there is some thought tyat Himmler (no fool) knew the war was lost and felt that ending it might lead to some negotiating room. As I said, the dying and killing continued, several thousand people from the camps were summerily shot during the withdrawl even after Himmlers order.
*For a certain defination of inefficient. They killed about a million people. But, morale in the units was awful and one of the reasons the chambers was invented was to make it less personal, the killings that is.
Sources: https://www.yadvashem.org/odot_pdf/Microsoft%20Word%20-%206373.pdf
https://www.yadvashem.org/holocaust/about/final-solution/death-camps.html
Peter Longleach Holocaust: The Nazi Persecution and Murder of the Jews
We have removed this submission as it certainly is not reflective of the standard scholarship on the topic and has strong echoes of common denialist talking points which attempt to transfer blame from Hitler to his subordinates, absolving him of culpability, most prominently but not limited to "Hitler's War" by David Irving. The simple answer is that this is most certainly not true, and you'd be hard pressed to give the title "mainstream historian" so someone seriously advancing such an argument. See below.