The East German Stasi did a number of strange things, but perhaps the strangest was its attempt to create a scent library of its population. It was analogous to a fingerprint library, and was based on the premise that everyone had a unique scent which could be used to track them, if need be. From Dog Law Reporter:
The most interesting use of police dogs concerned scent identification, a method analyzed by Dutch and other researchers, but adapted by the unique paranoia of the Stasi. As early as 1973, the Stasi began collecting smell samples of a large number of citizens. Sometimes this was done with a special chair that the subject was asked to sit on during a visit to the police station. The chair had a dust cloth on top of the seat that was clamped into place by a removable frame. The subject had to sit in the chair for ten minutes, but after the interrogation was over, the dust cloth was removed and stored in a glass jar.
Sometimes Stasi officials did not bother with being subtle and merely told subjects to put a cloth under their armpits or even under their pants in the groin area. The cloth was carefully handled by tweezers in an effort not to allow contamination by other human scents.
Stasi Smelling Jars