Trials typically begin with a list of charges being brought against a defendant, a list that usually takes just a few minutes to read aloud. But on May 11, 1987, 40 lawyers spent an entire day reading Klaus Barbie’s crimes aloud.

Hundreds testified, including a woman who had been just 13 years old when Barbie savagely tortured her. The French justice system turned itself inside out struggling to cope with its own troubled past and Vichy collaboration. With Barbie’s name leading the headlines, the world wrenched its way through a new series of agonizing reflections on the horrors of the Holocaust.

At the time, the sheer scope of Barbie’s crimes dominated conversation and news. Very few people, however, asked the obvious question: How had the aging Nazi war criminal, who played a role in the deaths of thousands, evaded justice for decades?

You had the feeling that a ferocious beast was coming into the cell. It was absolute terror. Lisa Lesevre, former Resistance member

The answer? A crime that wasn’t read out in court that day in May. The U.S. government saved Barbie’s life — and gave him a job that ensured he went on to commit even more atrocities.

Barbie was 29 years old when a train took him to France halfway through World War II. A dedicated member of the Nazi Party for years, he’d been given his biggest position yet: head of the Gestapo in Lyon — a city known as a hotbed of the French Resistance. Barbie set up his operation in the Hôtel Terminus and began a reign of terror that still sets Lyon’s history apart from that of the rest of occupied France. His mission was to round up, interrogate and deport or kill as many enemies of the state — Jews, Resistance fighters and other “undesirables” — as possible.

Part of the horror of Barbie was his insistence on being personally involved with the torture. Even within the Gestapo, many officers let the lower ranks dish out broken bones, beatings and sexual abuse. Not Barbie. Though he later parroted the familiar “just following orders” line, there was nothing banal or bureaucratic about the type of evil he represented. Some biographers have tried to explain Barbie’s tremendous personal capacity for violence, pointing to his abusive father or early Nazi Party membership as factors. They all agree on one thing: that “[h]e was a savage,” as Lisa Lesevre, a former Resistance member, described Barbie while testifying at his trial.

After surviving 19 days of interrogation at Barbie’s hands, Lesevre was deported to the women’s concentration camp Ravensbrük. She recalled on the witness stand that Barbie used to carry a swagger stick that he’d tap against his boots as he approached her cell, so she’d know he was coming. “You had the feeling that a ferocious beast was coming into the cell,” Lesevre testified. “It was absolute terror.”

Barbie’s trial revealed torture methods — previously unheard-of devices, dogs, rape and electric shocks — used on prisoners, including women and children. He oversaw the interrogation of French Resistance leader Jean Moulin, who’s still remembered in France as a martyr. Moulin endured doors slammed on his hands, hot needles shoved under his fingernails and floggings, all without talking … up to his death, mid-deportation, in 1943. Barbie claimed that Moulin killed himself, but it’s widely believed the Gestapo officer personally beat Moulin to death.

After the war, the French government struggled to re-establish itself, and many war criminals like Barbie disappeared in the process. But, despite the outcome of the Nuremberg trials, many former Allies hadn’t finished with the Nazis yet. The U.S. Army Counter Intelligence Corps recruited Barbie for his next intelligence position: spying on the new French government, which was thought to be infiltrated by communists. When Barbie’s cover was blown, the Americans arranged for him to be smuggled out of the country to join the swelling ranks of former Nazis hiding in South America.

Barbie was not built for a quiet life. He kept a foot in two continents, ascending the ranks of the Bolivian armed forces as he worked for the West German intelligence service under a pseudonym. His U.S. connections may have even made him central to the 1967 capture of Che Guevara and the 1980 Bolivian coup. Though the tireless efforts of Nazi hunters finally saw Barbie extradited to France in 1983, the full scope of his career was suppressed.

When Barbie finally stood trial, the American government apologized to France for protecting him. But U.S. authorities claimed then — and still maintain — that they knew nothing about Barbie’s Nazi past and had nothing to do with him after helping him escape to South America, says Gerald Steinacher, professor of history at University of Nebraska-Lincoln and author of Nazis on the Run: How Hitler’s Henchmen Fled Justice.

“Research in recent years has proven both claims false,” Steinacher says. “The U.S. intelligence services knew plenty about Barbie’s SS past, and the CIA had contact with the wanted Nazi criminal in South America.” Even worse? As late as 1966, Steinacher says, “Barbie was on the payroll of the U.S.-sponsored West German intelligence service.”

Barbie’s legacy remains frustratingly unresolved. He opted not to attend much of his trial, giving his victims little opportunity for closure. Just four years after his lawyer, who controversially argued that Barbie’s crimes were no worse than French colonialism, deferred his client’s two previous death sentences for life in prison, Barbie died of cancer. And despite FBI documents to the contrary, the U.S. still does not acknowledge its role in the Butcher of Lyon’s long, brutal career.

But unlike many who’ve committed mass atrocities, Barbie’s trial — televised around the world — revealed the depth of his crimes. Taking the stand at the trial, author and Holocaust survivor Elie Wiesel emphasized it best. “We have to talk, we have to bear witness,” he said. “All those who have come before you to talk, they will prevent the killers from killing again.”