They discovered that the inner workings of the lock included a spring, guide rail, bolt, baseplate and pin. The mechanism is largely complete but shows signs of damage.
You may have seen a lock like this on a gate or a door. This lock works by using a slider mechanism. The bolt slides across and stops the door, or gate, from opening. A slider mechanism like this ...
This door locking bolt and spring came from the crematorium at the camp. The Rifles Museum has several artefacts related to this, all reminders of the terrible crimes perpetrated by the Nazi regime.