On 11 September 1947 in Warsaw, Appellate Investigative Judge Jan Sehn, member of the Main Commission for the Investigation of German Crimes in Poland, acting at the written request of the First Prosecutor of the Supreme National Tribunal, this dated 25 April 1947 (Ref. no. NTN 719/47), in accordance with the provisions of and procedure provided for under the Decree of 10 November 1945 (Journal of Laws of the Republic of Poland No. 51, item 293), in relation to art. 254, 107, and 115 of the Code of Criminal Procedure, interviewed as a witness the person specified below, a former prisoner of the Auschwitz concentration camp, who testified as follows:
| Name and surname | Józef Kocięcki |
| Age | 46 |
| Religious affiliation | Roman Catholic |
| Citizenship and nationality | Polish |
| Occupation | teacher |
| Place of residence | Warsaw, [...] |
I was interned at Auschwitz on 22 November 1940. I remained there until 10 March 1943 as a Polish political prisoner number 6560. I worked with different kommandos [work details] First I was at the main camp, and then, in March 1942, I was transferred to the Birkenau camp. From my time at the main camp, I recall SS-Untersharführer Müller. I knew his name already during my time at the camp. Presently, I have easily recognized him in the photographs on public display. He is the one in the photograph signed “Kurt Müller”. At the main camp, he fulfilled the function of a Blockführer and was on some sort of internal duty, because he hung around the camp. Very often, he was at the gate, and as the kommandos were on their way back from labor, he hit the prisoners with a baton, kicked them unconscious, and on four occasions, I witnessed as he killed people that way. He would do this for no particular reason, so that we often wondered why he was acting that way.
In fall 1941 (September), over 10,000 Soviet POWs were interned at the main camp. Both in terms of food and living conditions, as well as clothing, they were treated even worse than we were. Nevertheless, they were forced to go to labor. On three occasions, I witnessed as these people, on their way back from labor, pounced on a potato cart they were passing. Having noticed this, Müller fell on them with a baton, and when this did not prove enough, he started to fire his revolver. I saw seven prisoners go down during one such shooting. On another occasion, there were four dead. On the third occasion, there were also a few casualties, but I did not manage to count them. People would swarm around the cart, fighting for a raw potato.
Finally, I witnessed as during a roll-call, on the Mützen ab command [caps off], one of my comrades was late to take off his cap. Müller fell on him, beat him up and kicked him. The man fell to the ground, showed no sign of life, and was carried away to the block by fellow prisoners.
The report was read out. At this point the interview and the report were concluded.