They came to his home - displaying a piece of paper indicating they had been watching the Moscow-based shochet and mohel - and barked, "Where are the Jewish books?"
As the now 89-year-old Brooklyn resident relayed to some 20 students and professors at the University of Pennsylvania on Nov. 10, the walls of his home were filled with volumes of the Talmud, commentaries on the Torah and books on halachah.
"They weren't interested in that," said Lifshits in Yiddish, translated into English by his grandson, Rabbi Levi Haskelevitch of Penn's campus Lubavitch House. "They were only interested in the literature from Schneerson, the Chabad literature that [I] had treasures of."
Lifshits, who is known by the worldwide Lubavitch community as Motl der Shochet, told those gathered at the Lubavitch House on Spruce Street that for following his rebbe, Rabbi Yosef Yitzchak Schneerson, he was given a choice: inform on his fellow Chasidim, or be sent to a place "from where no one comes back."
" 'You're telling them to build secret ritual baths, to not join the military,' " he recalled his interrogators saying, before switching tactics. " 'The Soviet regime would like to get [you] away from all that. You're only 21 years old. Go home and think it over.' "
Lifshits did take the opportunity to think. He told the audience that he concluded that there was no way that he could deny Judaism or the rebbe.
Referring to that week's Torah portion, "Lech Lecha," Lifshits said that according to the midrash, Abraham went through fire for his beliefs. How much more should he, who was not as great as Abraham, endure Soviet punishment?
"When they called [me] back, I said there's nothing to consider. I have nothing to share."
What followed were seven years in captivity, the majority in Siberia. According to Haskelevitch, his grandfather spent three years of his sentence performing forced labor in a gulag.
Lifshits recalled that temperatures in the frozen tundra fell 50 below zero during the day. Prisoners died from the cold, as well as from sickness and starvation, but because the ground was frozen solid, the guards could not bury the dead.
They left the bodies on the side of the road, he said, to be devoured by bears.
"It's impossible to describe how human beings survived in those conditions," said Lifshits.
The mohel spoke rather briefly, but his recently published memoir in Yiddish, Zichronos fun Gulag, goes further, spanning more than 60 years spent in Moscow before coming to America in 1993. Whereas others were able to leave Russia long before that, he stayed behind on the orders of Schneerson's successor, Lubavitcher Rebbe Menachem Mendel Schneerson.
One of just three mohels in Moscow, Lifshits was told by the rebbe that he had the zchus - "the merit" - to bring Yiddishkeit to Russian Jewry.
In an interview after the event - translated by a Penn law student who just happened to be one of the thousands of babies Lifshits circumcised over the years - the author said that his story of mesirus nefesh, of self-sacrifice in the face of impossible odds, should resonate with American Jews.
"People today should appreciate the time they live in - a golden age," he said. "Nobody is stopping them from being religious, from being Jewish."