Terrorism expert Jessica Stern’s book My War Criminal: Personal Encounters with an Architect of Genocide is a mesmerizing, unsettling, and revelatory memoir of the two years she spent talking with Radovan Karadžić, who was responsible for the death of more than 7,000 Muslim men and boys at Srebrenica during the Bosnian War and who continues to be an inspiration for white nationalists around the globe. Stern brings to bear her incisive analysis and her own deeply considered reactions to her interactions with Karadzic, while also offering a deeply insightful and sometimes chilling account of the complex and even seductive powers of a magnetic leader—and what can happen when you spend many, many hours with that person.

Radovan Karadžić, a psychiatrist and poet-turned-politician, is known by many names—“Bin Laden of Bosnia,” “Butcher of Bosnia,” and “Heinrich Himmler of the Balkans.” Said to be disturbingly magnetic and brilliant, he lived on the lam for over a decade, disguised as an energy healer. He was the subject of the largest manhunt in modern history prior to the hunt for Osama bin Laden. He was finally captured by Serbian intelligence in Belgrade in 2008. Karadžić was later convicted of genocide and other war crimes in 2016; his sentence of forty years was increased to that of life in prison in 2019.

For two years, between October 8, 2014 and November 11, 2016 Stern met with Karadžić in his prison in the Hague—the first time since the Nuremberg Trials that a researcher was allowed to conduct in-person interviews of a jailed leader on trial for genocide. Stern, one of the foremost experts on terrorism and the connections between trauma and terror, found herself wondering what led Karadžić and his followers to commit such horrendous acts. Just how do leaders persuade ordinary people to kill their neighbors? What happens when an ethnic or racial group loses its dominant position in society? How do leaders harness fear and weaponize it, inciting the group that fears it will be “replaced” to target minorities with violence?

Sadly, the questions that Stern pondered are ones that continue to need to be asked, as the genocide in Bosnia has become a model for the global white-nationalist movement. The Australian terrorist who killed 51 worshippers in two Christchurch mosques in March of this year had names of Serb nationalists painted on his guns. During his livestream of the brutal murders, the killer played a song glorifying Radovan Karadžić. Anders Breivik, the Norwegian terrorist who killed 77 people in 2011 said that Serb nationalists were a more appealing model than Nazis for the contemporary white-nationalist movement. He lionized Karadžić in his manifesto, calling him a “war hero” for his efforts to “rid Serbia of Islam.”

As Stern writes, when she first started doing this work some 30 years ago, a psychologist advised her that in order to truly explain terrorism to others, she would need to picture herself joining the group in question—in other words, she had to become the terrorist. “This ‘becoming the terrorist’ was, and remains, something that I am able to do,” Stern explains. “Not every time, and not every perpetrator. It worked with Karadžić. The conversations I had with Karadžić were unusually intense and unusually prolonged. He took up residence in my mind. I became a fellow prisoner, and he became ‘my war criminal.’”