In the years 1933 to about 1945, interrogations of prisoners were conducted by the Secret State Police (Gestapo) in the police prison in Klapperfeldstraße. These interrogations were conducted by Bauer, Huber, Ludwig, Datz and Rühlemann, among others. After 1934, a female typist took notes on the interrogation protocols.

Adolf Diamant reports:

»In the summer of 1933, a young man forgot a folder with anti-fascist leaflets in the Frankfurt tram as well as a printing matrix for the production of these writings, which were printed in Eschersheim. The folder came into the hands of the Gestapo, who did not have to search long for the persons who distributed the leaflets. The address was in the folder they found. It was a house in Eschersheim. The Gestapo immediately searched the house and arrested all the people in the house. Only one woman, who was at the Baltic Sea with her 10-year-old son, could not be arrested.

So Gestapo officers Rühlemann and another officer drove to the Baltic Sea and arrested the woman and the child and took them to Frankfurt. The child went to live with one of the woman‘s sisters, while she was taken to Klapperfeld prison, at the Gestapo‘s disposal. From there she was taken to the Gestapo for interrogation several times. She was accused of ‚preparation for high treason‘, and in order to extort a confession, they even had her child brought before them for interrogation. In the meantime, the producer and distributor of the leaflets was also apprehended by the Gestapo, and at the end of the month of October 1933, the woman was released from prison after about three months in custody.«

The Nazi opponent Johann Schwert from Frankfurt reports the following about his interrogation:

»…my doorbell rang and when I opened it I looked into the muzzles of two pistols which were held out to me. I was handcuffed, taken to the Klapperfeld police prison and immediately interrogated.

Gestapo man Bauer was sitting at the desk and two Gestapo men were standing behind me. If I did not immediately answer the questions put to me, the two Gestapo men immediately beat me. At the next table sat a secretary who operated the typewriter.

It happened several times that after an interrogation was over and I was taken to the cell, another Gestapo man came and then started another interrogation, accompanied by blows and kicks, so that I bled. These interrogations dragged on for about half a year.«

The Gestapo‘s interrogation methods were extremely brutal and there was repeated severe abuse.

In the Klapperfeld police prison, interrogations were carried out by the Gestapo during the day and at night. These interrogations could be divided into three levels:

1. Insults, threats, slaps, kicks, painful bondage, blackmail by naming accomplices.
2. maltreatment by rubber hoses, choking, hanging with the head tied down, pulling out tufts of hair
3. instruments of torture and extortion by parading family members.

Source: Adolf Diamant: Die Gestapo Frankfurt a.M., Frankfurt 1988 | Stadtarchiv Frankfurt am Main: Magistratsakten Sig. U/1.013