Warsaw, 11 November 1947. Judge Halina Wereńko, a member of the District Commission for the Investigation of German Crimes in Poland, interviewed the person specified below as an unsworn witness. Having been advised of the criminal liability for making false declarations, the witness testified as follows:
| Name and surname | Wacław Adolf Sterner |
| Names of parents | Józef and Helena née Neuging |
| Date of birth | 28 November 1908, Warsaw |
| Religious affiliation | Evangelical-Augsburg |
| Place of residence | Warsaw, Szustra Street 27 |
| State affiliation and nationality | Polish |
| Education | higher |
| Occupation | Deputy Director of the Warsaw Reconstruction Directorate |
The order to evacuate Mokotów was given on 25 September 1944. On 26 September in the morning, a couple of dozen people from the Yard Command, “Parasol” battalion group and Group B accessed the sewer through the hatch in Wiktorska Street, after which the hatch officer ordered a short break. After the break, which lasted longer due to an airstrike or artillery strike, a Polish People’s Army group entered the sewer, but soon returned because it was blocked before Puławska Street. On the evening of the same day, another hatch was opened, in Szustra Street, opposite the Tax Office, and then a “Parasol” battalion group, “Radosław” group, a group of the wounded B.III soldiers, Captain Garda’s group and local administrative units […] entered the sewer. Around 1.00 or 2.00 a.m. on 27 September, the wounded used a de-commissioned hatch at the junction of Bałuckiego Street and Szustra Street and blocked the sewer. Around 5.00 or 6.00 p.m., the passage through the sewer was opened and a group of around 150 soldiers from different units accessed the sewer.
At 5.00 p.m., Major “Burza” Landberger and Lieutenant “Nerus”, the commander of B.III Company, signed the act of Mokotów’s surrender. The hatch officers in Bałuckiego Street and Szustra Street were Lieutenant “Henryk” and Lieutenant “Adolf” aka “Bos”; they were the last ones to get into the sewer, closing the hatch behind them. I was in the last group to access the sewer. At 10.00 a.m. on 27 September, the Germans threw grenades into the sewer, near the location where the road starts to fall away towards Czerniaków.
People got out of the sewer within 24 hours, at different locations. On 27 September around noon, one such group was massacred by the Germans near the hatch in Dworkowa Street. At that time, I was in the sewer at some considerable distance from the execution site. The events were recounted to me.
At this point the report was concluded and read out.