[4] In January 1941 he was promoted to SS-Unterscharführer and transferred to Auschwitz, working as a medical orderly in the prisoners' infirmary.

[6] Due to various descriptions of him standing against a background of corpses "wearing either a white coat or "a pink-rubber apron and rubber gloves" and "holding a 20-cc hypodermic with a long needle" in his hands, Klehr has been described as the "ultimate caricature of the omnipotent Auschwitz doctor.

[7] As told by Witold Pilecki, who had first hand knowledge of Klehr's operations in Auschwitz "They were not exclusively those seriously ill or exhausted.

Klehr used to murder with his needle with great zeal, mad eyes and sadistic smile, he put a stroke on the wall after the killing of each victim.

In my times, he brought the list of those killed by him up to the number fourteen thousand and he boasted every day with great delight, like a hunter who told of the trophies of the chase.

As a handler of Zyklon B his tasks included not only delousing living quarters and clothes, but direct involvement in the mass gassing of prisoners.

He was transferred to the Gleiwitz subcamp in 1944 where he was head of the prisoners' hospital and was medically responsible for Glewitz camps I to IV.

[citation needed] Upon the evacuation of Auschwitz, Klehr guarded prisoners being transported to Gross-Rosen concentration camp, after which he was taken under command by an SS combat unit.

In April 1960 the Frankfurt prosecutor's office issued an arrest warrant which was executed in September after Klehr's whereabouts were determined.

[4] A witness, surnamed Głowacki, testified in court that Klehr killed the women who survived the massacre after the alleged uprising at the Budy female subcamp by phenol injection.