Ms. Sereny, a Viennese native, came of age as Adolf Hitler rose to prominence in Europe and became one of the foremost authorities on the crimes against humanity committed by the Third Reich.
She also wrote renowned books about murders involving children who killed other children. A 1999 New York Times review of “Cries Unheard,” about a notorious British child murder case, called her book, “an extraordinarily important and powerful work.”
“It will agitate, provoke, and poke and prod your preconceptions,” journalist Alex Kotlowitz wrote in the Times. “It will, I suspect, make it impossible to look at children accused of violent crimes the same way again.”
Ms. Sereny’s best-known books, however, concerned the Nazi regime. It was a movement she knew intimately.
As a youth, Ms. Sereny was mesmerized by Hitler as a charismatic leader and attended his 1934 rally in Nuremberg, later admitting to CBS’s “60 Minutes” that she “screamed ‘Heil!’ with the best of them.”
Her infatuation turned to disgust as she matured. While studying at the Sorbonne in Paris, she aided members of the French Resistance movement. After World War II, she served as a relief worker for the United Nations, tending to children who had been liberated from the Dachau concentration camp. Later, her duties included recovering children who had been stolen from their families as part of the Lebensborn program, a Nazi effort to create an Aryan super race.
She later worked as a reporter covering the Nuremberg trials and was fascinated by the Nazi officers who told the court that their only crime was loyalty to the cause.
“The more I met individuals who had suffered quite appallingly, the more I wanted to meet the individuals who had done it to them,” Ms. Sereny once said.
As an author, she was best known for her candid interviews with Nazi war criminals. She spent hours interviewing Franz Stangl, the commandant of the Treblinka extermination camp where nearly 1 million people died, and Albert Speer, the architect, high-ranking Third Reich minister and Hitler confidante.
Her closeness to her subjects, however, led some critics to claim that she appeared overly sympathetic to some of the men who helped carry out Hitler’s genocidal Final Solution.
Ms. Sereny spent more than 100 hours with Stangl while he was in a German prison, serving a life sentence for his role at Treblinka. To ingratiate herself with Stangl, Ms. Sereny brought the ailing man homemade soup to lift his spirits.
In her 1974 book “Into That Darkness,” Ms. Sereny wrote that Stangl — an unrepentant Nazi — ultimately admitted to her that he felt guilty about killing thousands. He died the next day.
She was later contacted by Speer, who had read “Into That Darkness.” He offered to speak with her about his own experiences within Hitler’s inner circle.