Of all the Nazi leaders, Heinrich Himmler had the most sinister reputation. As head of the SS and the Gestapo, he built a state within a state that kept occupied Europe under the Nazi yoke. Hitler tolerated his insatiable empire-building and plotting, mainly because he trusted Himmler to murder unlimited numbers of human beings without a qualm.
With his rimless spectacles and blank expression, Himmler's ice-cold personality became the embodiment of the Nazi racial utopia and its totalitarian methods.
Who was Heinrich Himmler, and how much can his private papers and photographs add to what we know about him?
The existence of these documents, which include his wife's diaries, has been known since they were taken from the Himmler family home at the end of the war by American soldiers.
But these new letters published by Die Welt may help historians to trace the evolution of Himmler's Weltanschauung (world view) in his early years, as well as his uniquely ruthless personality.
Born into a solidly monarchist and Roman Catholic family, the young Heinrich was radicalised by the Communist regime that briefly ruled Bavaria after World War I.
In 1923 Himmler took part in Munich's Beer Hall Putsch led by Adolf Hitler. The attempted coup failed and Hitler was jailed, but for a generation of young extremists such as Joseph Goebbels and Himmler, he became a hero.
The encounter gave Himmler, who had embarked on a career as a poultry farmer, the opportunity to exercise his talent for manipulating the thugs who made up the National Socialist German Workers' Party.
By this time he was already deeply immersed in anti-Semitic pamphlets, which helped him to form his ideology, which included everything from homoeopathy and vegetarianism to Teutonic paganism and occult theories of race.
In 1927, Himmler met a nurse who shared his eccentric beliefs: Margarete Boden, known as Marga. Seven years older than Himmler, her passion was alternative medicine and Himmler would later insist on herbal medicine gardens at all SS establishments, including concentration camps. Early pictures show an anxious, prematurely aged woman alongside a prissy, chinless young man.
In the late 1920s, Himmler was put in charge of Hitler's "protection squads", the SS. Granted the grandiloquent title of Reichsfuhrer-SS by Hitler in 1929, he set about creating the machinery of terror that would come into its own after 1933, when the Nazi dictatorship was established.
Himmler proceeded to terrorise all potential resistance to the regime, and to deprive German Jews of their rights, property and ultimately their lives. The first concentration camp, Dachau, was set up in 1933; ultimately, tens of millions of people would pass through Himmler's vast network of penal colonies, labour camps and factories.
After Hitler gave Himmler oral instructions to carry out the "Final Solution to the Jewish Problem", six million were murdered by his SS legions in death camps, evidence of which Himmler took good care to destroy. He took a particular satisfaction in killing Jewish women and children, warning that this was necessary to prevent a new generation of Jews from avenging their fathers.
As Himmler's power grew, so did his ambitions to create a racially pure world, sending explorers to Tibet in search of the ancestors of the Nordic race.
Marga shared his anti-Semitism: though she worked for the Red Cross during the war, her letters are full of vicious comments about "Jewish rabble" and "Polacks". When she was interrogated by the Allies after the war, Marga defended her husband by blaming Hitler for the order to exterminate the Jews.
Their daughter, Gudrun, remained loyal to her father's memory long after the war.
Himmler's conduct at the end of the war destroyed his credibility even among his fellow Nazis. In early 1945 he opened secret peace negotiations through a Swedish intermediary, Count Bernadotte, posing as a humanitarian whose only concern was for the welfare of Jewish survivors of the concentration camps. Yet in the last days of the war, Himmler gave orders to his camp commanders that no living prisoners were to be handed over to advancing Allied troops.
In his political testament, written just before he shot himself, Hitler stripped Himmler of all his offices and expelled him from the Nazi party.
Having fled in disguise, wearing an eyepatch, the fugitive SS chief was captured near Luneberg by the British. Three days later he committed suicide, using a cyanide capsule concealed in his mouth. He avoided justice, but not ignominy.