A 92-year-old former Auschwitz guard has testified at another alleged ex-guard's trial, saying it was impossible not to know what was going on at the Nazi death camp.

Jakob Wendel, a former SS guard who was convicted and served time in Poland after the war, testified Friday at the Detmold state court trial of Reinhold Hanning.

The 94-year-old Hanning is accused of 170,000 counts of accessory to murder on allegations he served at Auschwitz in 1943 and 1944. He's told investigators he never served in the part of the camp where most of its 1.1 million victims were killed.

Wendel, who arrived at the camp in 1942 but didn't know Hanning, told the court that anyone there for an extended period "knew what was going on," news agency dpa reported.