One directive seen by the AP, from November 1943 and marked Private and Confidential, instructed all camp commanders to keep visitors away from sensitive sites.

"During visits to the concentration camps, the bordellos and the crematoria are not to be shown. Visitors also are not to be told anything about these facilities," said the order, signed by the divisional commander of the SS, the elite unit that guarded the camps.

Couched in patronizing and dehumanizing language, documents from the earliest camps foreshadow a system that would define the word "genocide." They show that years before the mass-scale killings began at death camps such as Auschwitz, the intellectual groundwork of viewing categories of humanity as subhuman was already in place.

The records include two camps previously known to the Washington researchers but about which few SS documents were available. Sachsenburg and Lichtenburg in eastern Germany were among the first sites opened in early 1933 but were closed in 1937 when the system was restructured into larger camps that housed tens of thousands of prisoners. Afterward, both served briefly as women's camps.

"There are approximately 4,000 pages of material that no one else in no other archive has access to," said Joseph White, of the Center for Advanced Holocaust Studies at the U.S. Holocaust Memorial Museum, who has seen only a catalog of the ITS documents on the two camps.

"These were records that were always under the control of the SS. That's very rare to find for these early camps," he said by telephone from Washington.

Such documents could help trace the evolution of the camp system from its genesis, White said.

It was at Sachsenburg, for example, that the SS first used colored triangles sewn onto clothing to identify categories of prisoners, a method widely adopted later. Armbands with different markings denoted a hierarchy among the inmates, from kitchen workers to "seniors."

Files on the two camps seen by AP reveal an utter contempt by the SS not only for inmates but for civilian authority, at a time when Nazi rule had not yet taken full control of all institutions of power.

In Lichtenburg — a drafty, disused Renaissance castle — an officer reported to his commander that the "sharp cutback of bread and rations is having a negative effect" on the prisoners, who were looking "sleepy and tired" and increasingly ill, he reported. No response was found in the file of correspondence.

Among Sachsenburg's conduct reports was evidence of the commandant's blatant snub of a court in Dresden, which had asked for the "urgent release" of an inmate to appear as a witness in a trial. The commandant wrote back with a flat refusal.