Esteban Volkov, who witnessed the dying breaths of his grandfather Leon Trotsky – the exiled Russian revolutionary leader whose assassination in Mexico in 1940 had been ordered by archrival Joseph Stalin – and who devoted his final decades to preserving Trotsky’s legacy, died June 16 in Tepoztlán, Mexico.

He was 97 and had lived in the Mexico City suburb of Coyoacán since coming under the guardianship of Trotsky at age 13. His daughter Nora Volkow, who uses a different spelling of the family name, confirmed the death but did not provide a specific cause. She said her father became blind earlier this year and entered a nursing home in Tepoztlán, a town south of the capital.

Volkov was a retired chemical engineer when, in 1990, he opened a museum in the house on Calle Viena where he had lived with his grandfather. The timing coincided with the end of the Cold War and came a year before the collapse of the Soviet state that Trotsky, along with Vladimir Lenin, had helped create.

The purpose of the exhibition space was to bring renewed attention to the man Stalin had sent into exile amid a power struggle to lead the Soviet Union after Lenin died in 1924. Stalin painted Trotsky as a subversive and tried to erase him from Soviet history.

“We don’t ask for political rehabilitation because he doesn’t need political rehabilitation,” Volkov told the Los Angeles Times of his grandfather, who was granted asylum by Mexico’s left-wing president and moved there in 1937. “We want historical truth. … Truth is a basic element of progress. We cannot go anywhere without the truth.”

The Leon Trotsky House Museum is now run by the Mexican state and has more than 50,000 visitors annually.

Trotsky warned his grandson to stay out of politics for his safety, and he obeyed. The museum is not meant to serve as a temple to his grandfather’s politics but to elaborate on the political journey of a man who had been born Lev Davidovich Bronstein and came from a wealthy Jewish family.

Volkov was born Vsevolod Volkov Platonovich Bronstein on March 7, 1926, in Yalta on the Crimea peninsula which had been part of the Russian empire and remained so under the Soviets. After Ukraine gained its independence from the shattered Soviet Union in 1991, Crimea became part of Ukraine and still is, although it has been occupied by invading Russian forces since 2014.

Volkov’s mother, Zinaida, was one of Trotsky’s two daughters. Volkov’s father, Platon Volkov, was a Trotsky supporter who was later arrested and disappeared into Stalin’s prisons, reputedly murdered by the regime.

Zinaida was allowed to leave the Soviet Union with her son, then 5 years old, to visit her father, who had been exiled to an island in the Sea of Marmara near Istanbul. For reasons that only became clear to Volkov decades later, his slightly older half-sister, Aleksandra, was left behind – not to be seen again by him for 57 years.

In 1932, fearing for the safety of his daughter and grandson, Trotsky told them to go to Berlin. Within a few weeks, Zinaida fell ill with tuberculosis. Grief-stricken and suffering from depression, she killed herself, according to her son, by leaving her head close to an unlit gas oven in their apartment.

Friends sent the child to a school in the Austrian capital, Vienna, run by self-styled “disciples” of psychiatrist Sigmund Freud, before his uncle Lev Sedov took him to Paris in 1934. Four years later, Sedov was found dead in a Paris hospital while being treated for appendicitis, with many historians concurring he had been poisoned by Stalinist agents.

Volkov later reckoned that, in all, 30 of his relatives were killed or disappeared by Stalin’s regime or, like his mother, took their own lives. He was soon sent to Mexico to join his grandfather, who called him Esteban in the Spanish-speaking country.

Although he was a world away from Europe, Volkov was not entirely safe. In May 1940, he was shot in the foot during an attempt to kill Trotsky in his home. Gunmen, reportedly led by Mexican muralist and Stalinist sympathizer David Alfaro Siqueiros, broke through the security team and riddled Trotsky’s bedroom with bullets from automatic weapons.

Trotsky’s wife pushed her husband into a corner, and they both survived. But the gunmen then fired into the neighboring bedroom, where young Volkov had been sleeping. “I was very, very lucky,” he recalled in a 2012 interview with the Spanish newspaper El País. “A gunman shot six times into my mattress, but I’d jumped under the bed. I remember the terrible noise and the smell of gunpowder.”

Just months later, on Aug. 20, Volkov had returned home from school when he saw Trotsky bleeding to death but still standing defiantly in the arms of his bodyguards and his wife, Natalia Sedova.

“Keep the boy away. He shouldn’t see this!” he recalled his grandfather shouting.

The assailant, Spanish-born Stalinist Ramón Mercader, had found his way into the home under the pretense of being an admirer, then attacked Trotsky with a mountaineering ice axe he had hidden in his coat.

Volkov saw his grandfather’s bloodied body taken away on a stretcher. Trotsky, who with Lenin had helped overthrow the Russian Empire during the 1917 Bolshevik revolution, died of his wounds the following day at age 60.

Mercader was convicted and spent almost 20 years in a Mexican jail before moving to the Soviet Union, where he received a hero’s welcome. A friend of Cuban leader Fidel Castro, he died of lung cancer in Havana in 1978.

After the assassination, Trotsky’s second wife, Natalia, looked after Volkov throughout his teenage years. At the National Autonomous University of Mexico, he earned a degree in chemical engineering. He got a job as a chemical engineer at the Mexican pharmaceutical company Syntex and, through his work in the synthesis of steroid hormones, was involved in the development of the contraceptive pill.

He was married to Palmira Fernandez from 1953 until she died in 1997. In addition to his daughter Nora, who is director of the National Institute on Drug Abuse in Bethesda, Maryland, survivors include three other daughters, Veronica, Patricia, and Natalia; five grandchildren; and two great-grandchildren.

Volkov spent much of his life knowing little of the fate of his half-sister, Aleksandra, until he received a call in the late 1980s from a French historian, Pierre Broué, telling him she was alive in Moscow but dying of cancer. Amid Soviet leader Mikhail Gorbachev’s policy of glasnost, or openness, Volkov was granted permission in 1988 to visit Aleksandra.

“Aleksandra was always distressed that it was I who our mother took with her,” Volkov told the publication Workers Vanguard at the time. “It was Broué, who was first to find out why. Stalin had specified in the exit papers that she could only take her youngest child.” (Aleksandra also spent years in a labor camp in Kazakhstan, then a Soviet republic, as part of a roundup of people related to “enemies of the people.” She was freed after Stalin died in 1953.)

Volkov described his reunion with Aleksandra as bittersweet. They could barely communicate because he had forgotten his Russian, and she spoke no Spanish, English, or French. Nevertheless, he said at a news conference, “It was a little like people from a shipwreck who meet safe and sound on the beach.”

Volkov also used the visit to press the Soviet state to clear the name of his vilified grandfather, whose very mention was taboo for decades. (He was never officially rehabilitated.)

Nora Volkow remembered her father as “an extraordinary man who infected me with his passion for science, justice, and the truth, and who inspired me with his resilience. He liked nature, mountains, and the ocean, and loved music, with Shostakovich and Stravinsky as his favorites. He never stopped walking and even died while walking, outside his nursing home.”