German housewife Erna Petri was on her way home from a shopping trip near her wartime house in the Ukraine when she saw six naked boys hiding by the side of the road. As the wife of an SS officer, she realised that they were Jewish escapees. She took them into her home and fed them. Once she had gained their trust she marched them to woods near her house and shot each of them in the back of the head.

Petri’s sadistic violence against Jews and others during the war is one of a number of case studies in a new book by US academic Wendy Lower, called Hitler’s Furies, which documents the extent of female participation in the Holocaust.

There are other horrifying instances of random violence against Jews by the wives of German officials in the east. There was Johanna Altvater, who took a toddler by the legs and killed him by smashing his head against a ghetto wall. Then there was Liesel Willhaus, the wife of an SS official, who used to shoot at Jews labouring in the garden of her house in Poland, sometimes while her three-year-old looked on. There was Gertrude Segel, who allegedly trampled a Jewish child to death. And then there were the many wives of SS officers, such as Vera Stahli and Liesel Riedel.

While these cases unearthed by Ms Lower were extreme, she says they were by not exceptional. “There is an estimate of around 500,000 women circulating in the East during the war. Many thousands of these would have had some role in the Holocaust whether as secretaries administrating the mass murder or in a more direct form. Because of the lack of documentation, it’s hard to calculate figures. But we did some statistical analysis and the probability is that the number of Erna Petri could be multiplied several thousand times.”

Until now it has been imagined that the Holocaust was perpetrated mainly by men and that female involvement was marginal. However, Ms Lower’s research contradicts this. For example, for the massacres in individual towns in the east to take place, participation would have to have gone far beyond those who were just doing the shooting. “The killers had a whole support staff. These actions could last for many hours. They needed people to make food for the killers, they needed people to collect the clothes.”

And in the front line there were nurses like Pauline Kneissler who administered the Nazi policies of euthanasia to patients in hospitals, giving lethal injections to the physically and mentally ill almost every day for five years.

But most of the murders perpetrated by women in the east during the occupation were striking not because they were part of the killing machine but rather as individual acts of cruelty.

“To explain why they did it is complicated. But the fact that they don’t have that defence of following orders means that we are looking at a base motive. They were motivated by ambition, greed and obsession with consumption. Unlike the men, there was no peer pressure but a number of women have spoken about the influence of the men around them.”

One of the primary motives was the antisemitism that had been been inculcated from an early age. “The Nazis were clever in a very sinister way about getting into the education system.”

Few were prosecuted and even fewer convicted (only one of Ms Lower’s case studies, Erna Petri, served time).

Apart from a few cases such as the sadistic female guards at Belsen, women were often overlooked completely. Ms Lower says we now know that female participation was on a massive scale.