Secret messages
Secret messages, usually in the form of coded texts, contained information on prisoner living conditions, SS terror, criminal medical experiments, epidemics, killing methods, the number of prisoners and victims, the fate of Soviet POWs, the killing of Jews in the gas chambers, the burning of their corpses in the crematoria and burning pits, the plunder of victims’ property, and the extermination of the Roma people. Some of the secret messages from prisoners to their relatives also contained private information.