Before he became an international literary sensation last year at age 100, Hans Keilson was better known as a psychoanalyst and an expert in childhood trauma.

A German-born Jewish doctor whose career was derailed when Hitler took power in the early 1930s, he fled to the Netherlands and joined the Dutch Resistance as a counselor for children orphaned by the Holocaust.

He interviewed hundreds of young people and with his findings wrote a seminal study of “sequential traumatization,” the piling on of horrors, one after another. That academic treatise was his most widely recognized work — until last year, when an American publisher re-released two novels he had written about the Holocaust more than a half-century earlier.

The author Francine Prose catapulted Dr. Keilson to fame with a glowing New York Times review of both books. “Comedy in a Minor Key” (1947) and “The Death of the Adversary” (1959) were “masterpieces,” she declared, and Dr. Keilson was “ a genius,” one of “the world’s very greatest writers.”

The books won critical praise in newspapers worldwide. “The Death of the Adversary” became an instant bestseller; “Comedy in a Minor Key” was nominated for a 2010 National Book Critics Circle Award.

Dr. Keilson, who was 101 when he died of undisclosed causes May 31 in Hilversum, Netherlands, once said he was perplexed by the sudden adoration. “I’m not even a proper writer!” he told the British newspaper the Observer. But “maybe,” he added, “I did manage to produce something which goes beyond the everyday.”

Neither of the books found an audience the first time around.

“The Death of the Adversary” had enjoyed a fleeting moment of attention when it was first released in English in 1962. Time magazine named it one of the 10 best books of the year, alongside works by writers such as William Faulkner, Philip Roth and Vladi­mir Nabokov. “Comedy in a Minor Key” was never translated, and both soon fell out of print and into obscurity, where they remained for decades.

The novels were rediscovered in 2007 by American writer and translator Damion Searls, who stumbled upon an old copy of “Comedy in a Minor Key” in a bargain bin outside a Yugoslavian specialty bookshop in Austria.

Dedicated to Leo and Suus Rientsma, who hid Dr. Keilson in their home in Delft, the book is a darkly comic tale about the forced intimacy shared by a Dutch couple and their secret Jewish boarder. When the boarder dies of pneumonia, Dr. Keilson captures the couple’s efforts to get rid of the body in a series of plot twists.

Taken with the story’s domestic perspective on war, Searls resolved to bring the book back to the world’s attention. His English translation was published by Farrar, Straus and Giroux in 2010, along with a new release of “The Death of the Adversary,” originally translated by Ivo Jarosy in 1962.

The latter chronicles the growing, complicated hatred and fascination that a young Jewish boy feels for his persecutor — not Hitler, in the coded language of the book, but “my enemy” or “B.” As much as the narrator suffers, “B.” clearly suffers, too, as a victim of his own monstrousness.

That empathy for a reviled dictator brought the book fierce criticism in Israel when it was first published. Time magazine, on the other hand, called it “the profoundest explanation to date” of why so many people acquiesced to Hitler’s evil.

Prose agreed. “Rarely has a finer, more closely focused lens been used to study such a broad and brutal panorama,” she wrote, “mimetically conveying a failure to come to grips with reality by refusing to call that reality by its proper name.”

Hans Alexander Keilson was born Dec. 12, 1909, in Bad Freienwalde, near Berlin. His father was a textile merchant and a decorated veteran of World War I.

The younger Keilson finished medical school but, unable to practice because he was Jewish, found work as a swimming instructor.

His first book, “Life Goes On,” was published by the prestigious German publisher S. Fischer Verlag in 1933. Banned the following year, it became the publisher’s last book by a Jewish author before the implementation of Hitler’s anti-Semitic Nuremberg laws.

“My career is as a doctor and I write, it’s very strange,” he told Searls, who wrote about Dr. Keilson for the Believer magazine last year. “I lost both identities. I don’t know if that’s an advantage or a disadvantage.”

Dr. Keilson and the woman who became his first wife, Gertrud Manz, fled to the Netherlands together. Once there, they saw each other only rarely. Manz, a Catholic who could live openly, gave birth to their daughter in 1941; later, angered by Pope Pius XII’s failure to intervene far more publicly and forcefully against Hitler, she converted to Judaism.

Dr. Keilson went into hiding when the Nazis began their occupation of Holland in 1940. He joined the Dutch Resistance and, armed with a fake ID, traveled the country by train to counsel Jewish children who had suffered unimaginable losses during the war.

He continued to work for decades with Holocaust survivors and published his dissertation on sequential traumatization in 1979. That work was his way, he told Searls in an interview, of “finally saying Kaddish, the prayer for the dead.”

Dr. Keilson’s parents died at Auschwitz. Alhough they followed him to the Netherlands, he said he could never persuade them to go into hiding.

“My parents were the basis of my life. I still feel guilt over my parents, and it never ends,” he told the New York Times last year.

His first wife died in 1969. The next year, he married Marita Keilson-Lauritz. Besides his wife, survivors include a daughter from each of his marriages; and three granddaughters.

Dr. Keilson stopped writing fiction after the failure of his first three novels. He was glad the books had been rediscovered, he said. “They have gained new power of expression that they never had before. In America too, with a whole different audience,” he told Radio Netherlands in a recent interview. “It wasn’t written in vain after all.”

His first novel will soon be available in the United States, said Searls, who is translating the book. Dr. Keilson’s memoir was published in German last month and will likely also be translated into English.