Patrick Desbois, a Roman Catholic priest, has spent the last 15 years investigating and uncovering the details of Nazi massacres across Eastern Europe and Russia, crimes known as the "Holocaust by bullets."
During World War II, the Nazis killed some 1.5 million Jews and Roma across the Soviet Union. While the Nazi death camps are well documented, much less has been known about the systematic murdering of Jews in what are today Ukraine, Belarus and Russia and other countries.
Desbois changed that: He and his team interviewed nearly 6,000 witnesses, reconstructed the details of thousands of massacres and identified nearly 2,500 previously unknown execution sites.
Desbois founded a Paris-based nonprofit organization in 2004, Yahad-In Unum (Hebrew and Latin for "Together in One"), dedicated to documenting evidence of the Holocaust in Eastern Europe and preventing future genocides.
"We've been working now for more than 15 years to find the mass graves of Jews and gypsies [Roma] and disabled people shot by the German units and their collaborators," Desbois says. "So we've unconsciously transformed into a kind of specialist unit for mass shooting crimes."
Desbois, 62, says his team works with anthropologists and ballistics specialists and has developed a protocol for interviewing witnesses to allow them to remember, speak and provide as much detail as possible.
The French priest is now turning his attention to the Middle East. He is documenting crimes ISIS has committed against the Yazidi people, an ancient religious minority in Iraq.
Wearing wire-rimmed glasses, a black blazer and priest's collar, Desbois has a slight tan and a stubble beard left over from a recent trip to Iraq, where he heard Yazidi women recount stories of rape, executions and other crimes. He admits it is hard to listen to such horrific stories day in and day out. He says he prays a lot, and that he and his team have psychological counseling to be able to deal with it.
He says the Nazis and ISIS share many similar tactics, such as executing people in public and enlisting local help in their murders.
"Many times, Jews were shot in public like that, it was a show. And also the Germans used the Soviet system to have workers for free to do all the dirty jobs," he says. "There is no genocide without the neighbors."
Desbois says unwillingly or not, neighbors helped prepare for the killing, whether it took place in Poland, Ukraine, or Iraq. And strong ideology isn't the only motivation.
"In a genocide machine, there's never a pure ideology," he says. "Nazism and the ideology of Hitler was important, but sex and money was also important. The Gestapo had so many sex slaves in Russia. As for ISIS, when they arrested the Yazidis, they'd bring one bag for gold, one bag for telephones and one for jewels. The Nazis did exactly the same. The criminal is attracted by uber-power, sex and money."
There's a family story behind Desbois' crusade. In 1942, his grandfather was deported from France to a work camp in Ukraine. Desbois says his grandfather never spoke about what had happened in the village of Rawa Ruska.
"So I decided to go there one day," he says, "and that's when I discovered that the Germans shot at a minimum 18,000 Jews, plus gypsies, plus Soviet prisoners. But no one wanted to speak about it."
Desbois made that first trip in 1989. When he returned several years later, after the collapse of the Soviet system, everything was different, he says.
"The mayor of the city took me to a mass grave site with 50 farmers who had been present at the killing," he says. "And these people were ready to speak."
The mayor told Desbois that what he had been able to do in Rawa Ruska — listen to all the witness accounts — he could do in hundreds of other villages. Desbois says he never hesitated. The work is "God's calling," he says.
Ukrainian Kateryna Duzenko has been working with Desbois for the last eight years. She started as an interpreter in the field and now manages the Yahad-In Unum archives and website in Paris. She says many people contact Yahad-In Unum to try to find out what happened to family members killed in Eastern Europe during the Second World War.
"They know their family members were killed, but they don't know the details," she says, "like who rounded them up, where did they shoot them, on whose orders. We give them this information."
The group consults German and former Soviet archives, and between these and the witnesses' testimony, they have been able to put together a clear picture of the methodical way the Holocaust by bullets worked.
Duzenko says these mass killings are not a subject Ukrainians talk about easily.
"Because we know there was participation of local police in the murders," she says. "But as a Ukrainian, I need to know my history and to know what happened and accept that Ukrainians participated — and move forward to do better things in the future and to prevent the same thing from ever happening again."
Desbois believes that helping the Yazidis is also God's calling. Again, he says it was a personal experience that brought him to the Yazidis.
"I didn't pick one genocide over another," he says. "The call brought me to the Yazidis." ISIS has killed many people in Europe, he says, including a French priest, whose throat was slit in a church attack in 2016.
"I couldn't remain a bystander," Desbois says.
ISIS attempted to annihilate the Yazidi people — killing men, selling women and girls as sex slaves and taking away children to give to ISIS families or put in terrorist training camps.
His team's interviews with more than 200 Yazidi victims and witnesses will serve as corroborating evidence of crimes, along with photos taken of ISIS crimes. The testimonies will be made accessible to justice officials who are trying ISIS combatants for crimes against humanity in several countries.
Desbois says once he began documenting the crimes against the Yazidis, he knew he had to do more: This time, he had the chance to help the victims.
"I couldn't do an interview and just say bye-bye, I'll come back in one month. It was impossible for me," he says.
So Desbois' organization has set up two workshops in Iraq with sewing machines to help Yazidi girls and women who have lost their families. They are taught sewing skills so they can have a way to support themselves on their own. The organization is also working in camps for the displaced, helping orphans and other children, some of whom were forced to convert to Islam.
Desbois says mass killers specifically target "the other," whether Jews or the Yazidis — because they know the rest of the population is likely to look the other way. That's something he notes in his new book, In Broad Daylight: The Secret Procedures behind the Holocaust by Bullets.
Yahad-In Unum receives support from the European Union, French, German and American governments and family foundations in the U.S. and Europe. The organization has set up an interactive website with the material collected over the past decade and a half, including details of massacre sites and the testimony of those who witnessed Nazi crimes.
The priest says he has been contacted about investigating the atrocities against the Rohingya. But for now, he does not have the funding to do so.
Despite the Internet and social media bringing the world together, Desbois sees people becoming more entrenched in nationalism. And he sees Holocaust denial growing. "The majority of the world's countries don't even teach about the Holocaust in school," he says.
That is why Desbois is relentlessly pushing to reconstruct the Nazi and ISIS crimes with as much detail as possible. Desbois says people often ask him why he insists on getting so many details.
"And I say, 'if your mom was killed, would it be important to know who the killer was?' And of course it's yes. Everyone has the same answer."
Desbois says there's a tendency to see the Holocaust and other persecutions as a kind of global movement that we're helpless to fight.
"The Holocaust was not [a] tsunami," he says. "It was a personal crime."
The problem today, says Desbois, is that people think it was an unstoppable machine. "We speak about Hitler and Himmler," he says. "But in the end it is a person killing so many people. By himself with regular guns. These were not guns to kill millions of people."
Desbois says it's important to totally deconstruct the crime: "Where are the corpses, who did the killing? Which unit? Which person? Which locals were involved? Who were the victims?"
He says we must do this for the victims, but also to prove such killings are not an unstoppable, global force, but simple crimes.
"Because if we don't prove it was a crime," he says, "we dismiss the responsibility of the killers."
And that, says Desbois, gives carte blanche to the killers of tomorrow.