The communist tyrant Joseph Stalin was known as an anti-Semite who planned wide-scale purges against the Jews in his latter days.

But that may not have prevented him from having an affair with a Jewish woman and of taking care of her daughter until her mother died. According to some evidence, Stalin may have even married the woman.

The affair was disclosed recently following the discovery of a letter by historian Nicolai Nada. The letter, placed on the desk of the general secretary of the communist party Georgi Malenkov in 1953, the day Stalin suffered a stroke, was kept in a classified party file for decades.

A few months ago, officials in charge of the file were persuaded to reveal the letter, which reads:

Dear Comrade Malenkov!

I am the daughter of Ana Rubinstein, the former wife of Comrade Stalin.

As he is in ill health, I ask you to let me see him. He knows me since I was a child

If it is not possible to see him, I ask you to grant me an audience on a very urgent matter.

It is unknown what the writer sought to tell Stalin, or what the “urgent matter” she wished to discuss with the general-secretary of the communist party was about. Instead, Nada focused his research on the identity of Ana Rubinstein, “the former wife of Comrade Stalin,” and uncovered the following information:

n It appears that Ana Rubinstein was born around 1890 in Ukraine. In 1910 she married a Jew named Zalman Kostiovsky, and on Sept. 28, 1911 they had a daughter named Regina. The marriage broke up and a year later Ana came to Saint Petersburg with her daughter but without her husband.

n Nada believes Stalin met Ana Rubinstein as early as 1912. He used to visit Saint Petersburg often, where Rubinstein was affiliated with the city’s Bolshevik underground. The affair apparently developed later, because in 1913 Stalin was apprehended by police and deported to Siberia, returning in the spring of 1917. Regina Sabashnikov — whom Stalin knew during “her childhood” — was 5 in 1917.

It’s still not clear if this was just an affair or whether the couple actually married because all documents pertaining to Stalin’s personal life were confiscated in the 1920s, and Stalin personally destroyed “incriminating” documents.

The official version of his biography, published in the U.S.S.R., mentions two women: Yekaterina Svanidze, who died of tuberculosis, and Nadezhda Alliluyeva, who committed suicide. Indirect evidence shows that Rubinstein may also have been a legal wife.

The first piece of evidence concerns the timeline.

Stalin was first seen with the beautiful Alliluyeva in 1917 but married her 18 months later. In elite communist circles, it was whispered that the tyrant didn’t marry because he wasn’t divorced from his first wife. But Stalin’s first wife, Yekaterina Svanidze, died in 1907.

Another piece of evidence is linked to Rubinstein herself. Documents indicate that, for dozens of years, someone in high places took care of Rubinstein and her daughter Regina. Ana’s grandson, Vitali Sabashnikov, who died recently, told Nada that Rubinstein died in the 1950s in Leningrad. Sabashnikov said she lived in an elite neighborhood on Vasilievsky Island, opposite the house where the leadership of the communist party branch lived.

Ana and her daughter stayed in Leningrad during the siege, when 1 million residents died of starvation. The two survived the siege, likely because they received food packages from the party branch.

Later, Regina Kostiovsky married Vladimir Sabashnikov, an engineer. In September 1950, they moved to Moscow as a wave of anti-Semitism swept across the U.S.S.R.

But someone in the communist party made sure that the Sabashnikov couple be given a spacious apartment in a luxurious building near the Taganka Square, a kilometer from the Kremlin.

Also, immediately after moving to Moscow, Regina was hired as an engineer at a classified institute that developed innovative weaponry, months after the KGB issued a confidential decree not to hire Jews to work in security related institutions.

Even after she had dispatched a letter to general-secretary Malenkov, she was not fired and continued working there until her retirement. Nada considers this proof her mother was close to Stalin — because in 1953 those who made unfounded claims of affiliation to the “people” were deported to labor camps for “offenses against the reputation of the state.”

For six weeks, Regina’s letter sat on the desk of Malenkov, who was appointed prime minister upon Stalin’s death. On April 16, following a meeting attended by only a few senior leaders, Dmitry Sukhanov, director-general of the prime minister’s office, ordered the letter placed in the party presidents’ secret archives in a special file whose contents were meant to be kept confidential forever. The letter was kept in the file until the fall of the communist party and collapse of the Soviet Union.

Regina Sabashnokov died on Jan. 23, 1989 and was buried in a prestigious cemetery.