I believed that crematoriums could be erected fast and so wanted to burn the corpses in the mass graves in the crematory, but when I saw that the crematory could not be erected fast enough to keep up with the ever-increasing numbers exterminated, we started to burn the corpses in open ditches like in Treblinka. A layer of wood, then a layer of corpses, another layer of corpses, et cetera. To start the fire, we used a bundle of straw dipped in gasoline. The fire was usually started with about five layers of wood and five layers of corpses. When the fire was going strong, the fresh corpses which came from the gas chambers could merely be thrown on the fire and would burn by themselves.

To Leon Goldensohn, April 9, 1946, from "The Nuremberg Interviews" by Leon Goldensohn, Robert Gellately - History