I have personally observed a prisoner’s lungs burst. The rehearsals have produced such pressure on the heads of these men that they would go mad and tear their hair out in a desperate effort to alleviate the dreadful feeling.

These were the observations of Sigmund Rascher, an SS scientist in the days of the Nazi Empire. Although most people remember Joseph Mengele, the truth is that Dr. Rascher conducted equally cruel and aberrational experiments. Everyone in the Third Reich knew him because he had the full confidence of Heinrich Himmler, one of the most important Nazi hierarchs. Hundreds of people fell victim to Rascher, who was obsessed with proving his wild medical theories.

Sigmund Rascher was born on February 12, 1909, in Munich, Germany, into a wealthy family. Since he was a child, he knew that he would follow in the footsteps of his father, who was a doctor. So at the age of 21, he enrolled in the university to study medicine. At the beginning of the 1930s, he showed an interest in the ideas of Nazism, which preached hatred towards the supposed inferior races, communism, and democracy. However, he did not join the National Socialist Party until 1933.

Rascher always insisted that he joined the movement before Hitler came to power, but documentation shows that he did so after the Führer had become master and lord of Germany. This shows that from the beginning of his career, he took advantage of every opportunity that came his way in order to consolidate himself as a scientist.

For some time, Rascher worked as an assistant in his father’s medical office. On the other hand, he tried to climb positions within Nazism and joined the SA, that is, the Brownshirts. In 1939, he joined the SS and entered the Leibstandarte, one of Hitler’s most devoted military bodies. That same year, Rascher reported his own father to the Gestapo, accusing him of anti-Nazi behavior. This fact earned him enormous prestige within the movement because he demonstrated that his fanaticism was so great that he was capable of betraying his family for the National Socialist cause.

His meteoric rise did not stop there but continued as he married Nini Diehl, a former actress and singer. Diehl had been the mistress of Heinrich Himmler, with whom she was still on friendly terms. In fact, it was common for her to write to the SS leader asking for favors such as money, food, or reduced taxes. Thus, thanks to his new wife, Rascher managed to get closer to the most influential social circles of the Third Reich.

Barely a week after meeting Himmler, the doctor presented him with a project to cure cancer through a treatment with plants, although he warned him that it was necessary to use humans as guinea pigs. The SS leader agreed and authorized the plan, which although unsuccessful, served to connect these two men as they shared a twisted interest in science.

Starting in the spring of 1941, Sigmund Rascher began his most bloody and abominable experiments. At the time, the Luftwaffe was developing an aircraft capable of climbing to high levels to evade British fighter bombers. In this context, Rascher offered to lead an investigation into the effects of depressurization and high altitudes. He wrote Himmler a letter asking permission to experiment on concentration camp prisoners, something the SS leader enthusiastically authorized.

The research was conducted in a decompression chamber from which air could be extracted to simulate conditions at 20,000 meters high. People were introduced into the apparatus, and once inside, the oxygen was removed to observe their reaction. Some died instantly, but others went into convulsions, their faces distorted and their eyes swelled until they looked as if they were going to burst. As we told you at the beginning of the video, a brutal end awaited these patients. The tests in the depressurization chamber did not provide any significant information, so Rascher’s victims died in vain.

In 1942, he conducted another round of experiments, this time in below-freezing conditions. The objective was to solve the problem of airplane pilots who, after crashing, fell into icy waters and died of hypothermia. Rascher asked Himmler for 300 concentration camp prisoners to use as guinea pigs. Some were forced to remain naked for 14 hours in the open field in the middle of a heavy snowfall. Others were submerged in a tank of ice water for three hours while their vital signs were monitored with electrodes. Next, the patients were rescued from the cold, and different ways of warming them up were tried. The most harmless methods consisted of giving them alcohol or covering them with blankets. The cruelest, however, were based on immersing them in tanks of boiling water or injecting hot liquid into their stomachs.

Soon after, Himmler approved Rascher’s latest craze: an experimental drug called Polygal, supposedly able to stop bleeding. To demonstrate this, the scientist forced his patients to ingest the drug and then ordered them to be shot in the chest and neck. Others underwent limb amputations without anesthesia, all with the aim of proving that bleeding decreased as a result of Polygal.

Rascher’s downfall came in 1944 after a series of mistakes and missteps. The scientist had deceived Himmler, announcing that he had found a way to extend the fertile period of women, thus they would be able to have children until an advanced age—something that caught the attention of the SS leader, who was obsessed with increasing the birth rate.

Rascher announced that his wife Nini had given birth to three children despite the fact that she was almost 50 years old. However, what was actually happening is that the scientist was instructing his assistant, Julie Muschler, to steal infants, falsify documentation, and pass them off as his children.

The Rascher couple went to the extreme of murdering their accomplice to erase the traces of their crimes. Julie, the assistant, was summoned to a cabin in the mountains far from the cities, and once there, the scientist strangled her with his bare hands. The body was left out in the open, and for two years no one found it.

In 1944, Rascher’s wife was arrested at a train station while trying to kidnap a baby. The subsequent investigation revealed that the couple’s children had been stolen from other families and that their own assistant had been killed.

Himmler was furious, and as punishment, he sent them to concentration camps. Sigmund Rascher ended up detained in Buchenwald and later transferred to Dachau, while Nini Diehl ended up in Ravensbrück, where they remained locked up for months.

On April 26, 1945, when the Third Reich was on the verge of defeat, Himmler ordered the execution of the former SS scientist. According to a witness, the executioner shot him with his rifle and left him to bleed to death on the ground while he did not stop kicking him. Finally, he finished him off with a shot to the head.

Shortly after, his wife was sentenced to death by hanging by piano wire. Thus concluded the story of one of the worst criminals of the Third Reich.

But the story does not end with the hangman’s wire. What Rascher left behind was not merely a catalog of atrocities but a paper trail—meticulous, cold, and damning—that would surface in the Nuremberg trials and haunt the medical profession for generations.

When Allied investigators entered Dachau in the spring of 1945, they found the remnants of his kingdom: the decompression chamber, rusted but intact; the freezing tanks, still stained; and filing cabinets crammed with charts labeled in his neat, obsessive hand. Each page recorded temperatures, pulse rates, convulsion times—the anatomy of suffering reduced to columns of data.

At the Doctors’ Trial of 1946–47, prosecutors introduced Rascher’s own reports as evidence against the Nazi medical establishment. His meticulous notes, intended to secure his legacy, instead became the rope that hanged his colleagues. “The defendant’s experiments,” the tribunal concluded, “were murders disguised as science.”

Yet the most disturbing discovery came later. Among the Dachau files, investigators found a proposal Rascher had submitted to Himmler in early 1944—one that had never been approved. It described a new series of tests involving the transplantation of human organs between prisoners, coupled with experimental sterilization techniques. The document bore Himmler’s marginal note: “Promising. Discuss after the war.”

That phrase—”after the war”—reveals the terrifying scope of what might have been. Rascher’s death was not the end of his ideas; it was merely the interruption of them. Several of his assistants survived the collapse of the Reich and slipped into civilian life, their names erased from the records they had helped compile.

One of them, a laboratory technician named Ernst Bauer, was later traced to a small clinic in Bavaria, where he practiced as a physiotherapist until 1958. When questioned by West German authorities, he claimed he had merely “followed orders” and “never harmed anyone personally.” He was never charged.

Nini Diehl’s execution, meanwhile, closed only one chapter. Her letters to Himmler—vain, grasping, full of petty requests—were discovered in a private collection in the 1970s and published by a German historian. They painted a portrait not of a monster but of something more banal: a woman who traded in favors, who looked away, who asked for sugar rations while her husband’s victims froze to death in the courtyard below.

Today, the site of Rascher’s decompression chamber at Dachau is marked by a simple plaque. It does not mention his name. Visitors walk past it on their way to the crematorium, often without stopping. The chamber itself was demolished in the 1960s, its metal sold for scrap.

But historians continue to debate the question the video posed at its outset: was Rascher worse than Mengele? The answer, perhaps, lies not in body counts but in intent. Mengele was a true believer in racial purity; Rascher was a careerist who believed in nothing but his own advancement. One killed for ideology. The other killed for a promotion.

Mengele vanished into South America and died a free man; Rascher was butchered by his own masters in a muddy ditch. In the end, the Reich devoured its servants as casually as it had devoured its victims.

Yet the question lingers, refusing to be buried with him. In 2015, a German medical journal republished Rascher’s altitude reports—not as history, but as a case study in research ethics. Students read them and asked the same question the tribunal had asked seventy years before.

“How could a doctor,” one of them wrote in the margin, “forget the patient?”

That is the true legacy of Sigmund Rascher: not the tanks or the chamber, but the reminder that science without conscience is merely cruelty with a clipboard. His victims have no graves. Only his neat, obsessive columns remain—and the silence of those who walked past the plaque without stopping.

So we return to the question that began this story. Was Rascher worse than Mengele—or merely a different species of the same disease? Tell us in the comments below: can a man who kills for a promotion be judged differently from one who kills for a cause?