During the last months of the war he held a central position at the Espeland detention camp in occupied Norway, where he became notorious for sadistic behaviour and torture of prisoners.

A member of the Nazi Party since 1934, he trained as a radio operator in the Luftwaffe and from November 1938 he served in the German border police.

[1][4] In 1945, the head of SiPo in Bergen, Ernst Weimann, needed a way to tighten lax conditions at the nearby Espeland detention camp.

Being aware of Runzheimer's cruel character, Weimann solved both problems by transferring him out of Bergen to Espeland, where he was assigned as a special guard tasked with enforcing a stricter regime.

[1] The camp commander at Espeland, SS-Oberscharführer Georg Eberl, had been treating prisoners reasonably well, but this changed with the arrival of Runzheimer on 1 March 1945.

Fearing consequences for their brutal treatment of camp prisoners, many of the guards (including Runzheimer) abandoned Espeland shortly before it was liberated by Norwegian police.

However, many of the officers had left portraits of themselves hung up on the walls inside the barracks and this enabled prisoners to identify the worst offenders to the authorities.