On the third day of what is likely to be one of the last trials of its kind, the 94-year-old told a court that he was aware of the conditions endured by prisoners at the Stuffhof site, but played no role in the killings that took place.
Rehbogen – who can be named but not pictured in the media – has been charged in Germany with being an accessory to hundreds of deaths during his posting between 1942 and 1944.
Prosecutors argue that his job would have meant he helped the camp to operate, but there is no evidence linking him to a specific crime.
In a statement given at the Muenster state court, Rehbogen – from Borken, near the Dutch border – claimed not to have opposed his position for fear of retribution.
More than 60,000 people died at the camp, which was near what is now the Polish city of Gdansk.
Inmates were killed in a gas chamber or by petrol or phenol injected directly into their hearts, while others were shot or starved to death.
Many were also left to die outside during the winter months, when they were forced outside without clothes until they died of exposure.
Around 20 of those who survived their time at the camp may be called to serve as possible witnesses during the trial.
Because of his age and health, Rehbogen – who uses a wheelchair – is limited to attending court proceedings for just two hours a day, with no more than two non-consecutive days a week.
The trial is expected to last until January.