[4][5] On 1 June 1943, one month before her 55th birthday, she was granted permission to stay on staff as a female overseer at Ravensbrück, despite her age.

[6] She was one of the first chief woman officers at Ravensbrück from 1939 to 1941, and took an active part in the selection of internees to be gassed during 1941 at the Bernburg Euthanasia Centre near Berlin.

She reportedly "liked to slap", "lashed out with her jackboots" and "walked up down the ranks carrying a large document file, with which she would beat inmates about the head for the slightest movement or sound".

[6] Zimmer referred to prisoners as “bitches” and “dirty cows” who needed to be put into their place[7] and "abused and bullied them in an extreme way.

[9] She was hanged by the British executioner Albert Pierrepoint on the gallows at Hamelin Prison on 20 September 1948, when she was 60 years old.