Editor’s Note: A version of this will be published in the Moscow opposition newspaper Novaya Gazeta.   One of the last and irrepressible truth-tellers about the Stalin era, who themselves experienced the horror of those years, has died. Having lost both his mother and father in the 1930s, in the tyrant’s prisons of torture and execution, Anton Antonov-Ovseyenko was arrested three times (in 1940, 1941 and 1948) and spent nearly thirteen years in Gulag forced-labor camps, including the infamous complexes at Pechora and Vorkuta.

Anton had one mission, as he passionately declared in my presence many times during our thirty-seven-year friendship: “To unmask Stalin, his henchmen and their heirs.” The first major result was Anton’s book Portret tirana (Portrait of A Tyrant), written in the 1960s and 1970s, long before it could be published in Russia, but published in English in New York in 1981 as The Time of Stalin. It remains one of the monumental works of historical truth-telling of the pre-Gorbachev and pre-glasnost era, along with Roy Medvedev’s Let History Judge and Aleksandr Solzhenitsyn’s The Gulag Archipelago.

Though legally blind—Anton needed special devices in order to read and write—and working surreptitiously and almost alone, the amount of forbidden information he uncovered, largely in oral and typescript memoirs of other surviving victims, and the volume of his writings were astonishing, even heroic. Researching before Gorbachev ended historical censorship in the late 1980s and before the post-Soviet “archive revolution,” Anton made some factual errors, which today’s historians must certainly understand and forgive.

As the historian Vladlen Loginov observed in an introduction to one of Anton’s books later published in Russia, “Every era gives rise to its own specific types of sources.” But the larger truth Anton revealed about “the monstrous crimes of Stalin” can no longer be denied by any serious historian, despite attempts to do so today in Russia and elsewhere.

As we might expect from his own history, Anton was a complicated man. His father, Vladimir Antonov-Ovseyenko, who led the Bolshevik seizure of the Winter Palace in 1917, was a founder of the Soviet state. Anton’s fealty to his martyred parents probably explains his reluctance to explore the origins of Stalinism in earlier Soviet history. He was also difficult in personal relationships, much like Solzhenitsyn. During the years I knew him, Anton’s uncompromising, sometimes willful nature alienated more than a few of his former friends, allies and even family members. This too was, in part, a result of his missionary commitment to truth-telling. It was also what bought him to the attention of Yuri Andropov, in 1982, then head of the KGB.

Reacting to the publication of The Time of Stalin abroad, Andropov ordered a day-long search of Anton’s Moscow apartment, while harshly condemning, in a secret report to the Kremlin leadership, his “illegal and anti-Soviet” activities. (I had taken the manuscript to New York, which may have been one reason why I and my companion Katrina vanden Heuvel—now The Nation editor and publisher and my wife—were unable to obtain Soviet visas again until Gorbachev came to power in 1985.)

As the years have passed, the legacy of Anton Antonov-Ovseyenko in Russia seems secure, and at least twofold. First, there is the enduring credo he wrote during the repressive Brezhnev years for all anti-Stalinists, including those struggling against the despot’s growing reputation in Russia today: “It is the duty of every honest person to write the truth about Stalin. A duty to those who died at his hands, to those who survived that dark night, to those who will come after us.” Second, there is the unique Museum of the History of the Gulag, which Anton founded in the very center of Moscow in 2001 and opened in 2004. Now growing in importance in the determined hands of a new generation of young truth-tellers, who are his progeny, the museum will long be his institutional legacy.

As for those of us privileged to have known Anton Antonov-Ovseyenko for many years, we know who Russia—indeed all of us—have lost.