Strange as it is to say about an exhibition covering murder and torture, one of the most poignant items in the Wiener Library’s new look at the victims and perpetrators of Nazi human experimentation is about marital breakdown.

It comes in the testimony of a woman who was forcibly sterilised in Stutthof concentration camp. She suffered terribly from different experiments. “That was agonising pain... I had a husband, but I couldn’t bear any children [and] as a result he divorced me.”

It’s just one, tiny consequence of the Nazis’ programme of non-consensual medical experimentation, which saw up to 27,000 people (including potentially as many as 4,364 Jews) experimented on in the most brutal ways. Many did not survive

“It’s heartbreaking,” says Dr Christine Schmidt, Head of Research at the library. “It’s not necessarily what the scientists who conducted those experiments intended, but it’s the human cost.”

It is this human cost that the library has sought for the first time in the UK to bring to life, using photographs, testimony and other materials. For while Josef Mengele’s twin experiments are well known, more than 70 years on the full story of Nazi experimentation remains in the shadows. “It’s considered something mad scientists did, there isn’t an understanding of the longevity of issues that arose from this period,” says Schmidt.

What the exhibition shows is that these experiments weren’t a niche practice. The scale was immense, from state-sanctioned “euthanasia” centres to individual scientists who saw ample opportunity in using prisoners they considered sub-human to further their careers. Victims were subjected to myriad inhumane experiments; injected with hepatitis to prove it was infectious, castration, X-ray sterilisation, or simply murder so scientists could research their brains and bodies.

For the victims, it was, unquestionably, torture. “I was unable to describe the agony I felt being completely helpless in the hands of the so unscrupulous tormentors to whom the life of a concentration camp inmate meant less than nothing,” recalled Iwan Ageew, who was experimented on in Dachau.

The exhibition tells some of their stories, including that of the women in Birkenau’s Block 109, murdered so their skeletons could be used for “racial” study. A picture of the Csengeri twins is captioned to explain that Mengele injected them with pathogens. There were the Ravensbruck “rabbits” — Polish female political prisoners experimented on by SS surgeon Karl Gebhardt as he investigated war wounds such as gangrene. As the caption reads, “physicians used surgery to inflict injuries, rather than as a treatment.”

Victims’ names are projected into the space; their identities known thanks to Paul Weindling, Wellcome Trust Professor at Oxford Brookes University, who has dedicated his career to this aspect of Nazi history and to uncovering the personal stories. “By looking at each experiment and each victim, a composite picture emerges,” he says. “We now commemorate Holocaust victims as individuals and give them the dignity of their name, and reconstruct their biographies. But it is a new idea to commemorate the victims of research by their full name.”

Among the victims were at least 25 Britons, including Jews who had lived in Belgium or the Netherlands, and British prisoners of war. As Weindling explains, PoWs were dosed with crystal meth, and also tested on the Sachsenhausen concentration camp “shoe track”, a cobbled path on which prisoners were marched 30 miles a day, seven days a week and then executed.

Some 10,000 mentally or physically handicapped children, were murdered in so-called special wards, while while others were used in vaccine experiments. Mengele experimented on perhaps as many as 732 Jewish twins — although as Weindling notes, some actually pretended to be twins to try and survive. “It shows the desperation, the choiceless choices that people faced,” says Schmidt. “Obviously it’s all awful, but when you’re talking about children there is something quintessentially evil and horrific.”

The exhibition acknowledges that such non-consensual research was not unprecedented, but emerged out of eugenics and the idea that certain groups were expendable or inferior. Other countries had practiced forced sterilisation, including the US. “The Nazis didn’t invent it but they took it to the extreme,” explains Schmidt.

And they did so with the enthusiastic support of the German medical establishment, despite their Hippocratic Oaths. “Nazi medicine was a nightmare of science put to destructive ends,” says Weindling. “Nazi medical researchers took advantage of the Holocaust to pursue research agendas.”

There was, adds Schmidt, almost no resistance. “The Nazi regime gave extensive professional opportunity to medical researchers, so there was little incentive to step outside of that.” One of the most discomforting exhibits is a 1943 copy of The Lancet, discussing research conducted in Buchenwald, which concluded: “We leave our readers to make their own deductions.”

Experiments happened in hospital wards and research centres out in the open, with studies often instigated by scientists. Pharmaceutical companies, industry and the military also benefited, for example Salamander Shoes used prisoners to test the endurance of their wares in Sachsenhausen.

And while some was “mad science”, undertaken seemingly for sadistic pleasure and not properly controlled, other experiments led to breakthroughs. “You had things like the development of lifejackets coming out of Sigmund Rascher’s experiments with people in freezing water,” explains Schmidt. “It brings up all sorts of ethical questions. Do you use that research, do you start over? Do you recreate the conditions in a more ethical way?”

After the war, the Nuremberg Code was signed, setting out the rights of research subjects to informed consent. “The legacy of the Nazi experiments was not great medical discoveries but the ethical protection of patients,” explains Weindling. “Every time we are asked to give consent, we can be grateful to the protests of victims and fellow prisoners.”

Yet justice was much slower, with post-war Germany reluctant to confront what had happened, and many victims were never compensated (the British Foreign Office also did little to help British victims challenge this).

“When the twins Jona and Miriam Fuchs applied for compensation in 1960 they were rejected,” says Weindling. “The position of the German Ministry of Finance until the revelation that Mengele was dead in 1985 was that a ‘twin experiment’ was anthropological and not medical, and not harmful to health, so no compensation was payable.” Compensation for surviving victims was calculated in terms of loss of earning capacity. “This meant that X-ray sterilisation victims, including many women who did not work outside the home, received only minimal compensation or none at all.”

While some scientists were brought to trial, many were not. Heinrich Gross, who conducted research on children murdered so their bodies could be used for research, became a celebrated forensic psychiatrist. The truth emerged 60 years later, but he was never tried. “He was personally collecting children to be murdered and he continued on with his profession after the war. He was praised for scientific achievements based on material he obtained very problematically,” says Schmidt. “And he walked off scot free.”

Germany’s medical establishment was likewise slow to address its dark past; it was only last year that the influential Max Planck Society acknowledged that its archives contained euthanasia victims’ brain tissue. But in some ways it’s not surprising to learn this; given the scale of what happened and the infrastructure it required, from doctors to nurses to technicians, it’s clear many people who carried on working in the medical establishment after the war must have been involved.

“You had to rebuild the country, there were people who were needed,” says Schmidt. “Right afterwards you had all these survivors of the camps, there had to have been medical staff around and they weren’t all part of the allied troops.”

The extent of collaboration, and the full scale of what happened to the victims, may never be known. In the course of constructing the exhibition, Weindling came across a “new” victim and the likelihood is there are many more to find. This is a story that for years was shrouded in secrecy, perhaps partly because it happened alongside, but apart from the Holocaust, and also because, in the midst of the horror of the Nazi era, some victims may not have known they were being experimented on and understood it only as torture. Others, who underwent procedures like castration, may not have spoken up out of a misplaced sense of shame.

This is the first exhibition the Wiener library has staged to have an age rating (16 plus); as Schmidt says, it’s a subject that was hard for victims to talk about and is hard for people to consider even now. “Most of us trust doctors and look to science to improve our lives,” she says. “In this case, for the idea that it would improve one particular population’s lives other populations were sacrificed. It’s a difficult thing to confront.”

Science + Suffering: Victims and Perpetrators of Nazi Human Experimentation, until 29th September 2017. www.wienerlibrary.co.uk