Holocaust survivor Jacqueline Mendels Birn, center, greets another Holocaust survivor, Margit Meissner, at the United States Holocaust Memorial Museum on Tuesday in Washington. (Marvin Joseph/The Washington Post)

The sound of Jacqueline Mendels Birn’s cello filled the Hall of Remembrance like a lament.

The notes, low and sorrowful, were those of “Ani Ma’amin,” a song of Jewish faith said to have been sung by concentration-camp prisoners on their way to the Nazi gas chambers during the Holocaust.

It was a sound like a human voice, said, Birn, 79, a French Holocaust survivor, who wore black earrings and black clothing in the Holocaust Memorial Museum on Tuesday as she played a requiem for the lost millions.

As Birn and her quartet performed, assembled dignitaries stood and then filed around the hall to light candles in honor of the dead during a museum observance of International Holocaust Remembrance Day.

The ceremony marked 70 years since the liberation of the Auschwitz concentration-camp complex by the Soviet army on Jan. 27, 1945.

Holocaust survivors and other attendees light candles in the museum’s Hall of Remembrance at the United States Holocaust Memorial Museum in Washington. (Marvin Joseph/The Washington Post)

During the ceremony, Holocaust survivors spoke to the gathering, victims’ names were read, and one survivor, Manny Mandel, recited kaddish, a traditional prayer often said in mourning.

“We say kaddish today for all those for whom there is no one to say kaddish,” he said.

The prayer was followed by a moment of silence.

Before that, Steven Fenves, 83, a retired engineering professor, had talked to the audience about his Holocaust experience.

He said he remembered being expelled, at 13, with his family from their home in Yugoslavia and then put on a train to Auschwitz.

“People lined up on the stairwell to ransack the house, spitting at us, yelling at us, cursing as we were led out by the gendarmes,” he recalled.

“At Auschwitz, I was immediately separated from my mother and sister, and eventually placed in what was called the boys’ barracks,” he said.

More than two dozen Holocaust survivors and guests attend the Observance of International Holocaust Remembrance Day at the United States Holocaust Memorial Museum in Washington. (Marvin Joseph/The Washington Post)

It was a place “where thousands, maybe 10,000, inmates were kept as livestock is being kept in the stockyards,” he said. The boys were available for selection to work as slave labor in German factories, mines or military sites.

[Survivors of Auschwitz tell their stories.]

Fortunately, the foreman didn’t consider the boys strong enough and always passed them by. Still, he said, boys, sick and starving, died daily and “were carted away in the morning with the dead of the night.”

He was saved because he spoke German and, later, Polish, and could serve as an interpreter.

His mother perished in Auschwitz, but a sister survived, as well as his father, although the father was, by then, a shattered man — “old, shrunken, emotionally, physically broken,” Fenves said.

“He died four months later, never . . . able to accept the idea that our mother was not coming back,” he said. “But at least we could bury him.”

Fenves eventually made his way to the United States and made a career as an academic. He lives in Rockville.

At least 960,000 Jews were murdered at the vast Auschwitz complex during World War II, along with about 125,000 Poles, Gypsies, Soviet POWs and members of other nationalities, according to the Holocaust museum.

Countless others were psychologically damaged.

Auschwitz was the largest Nazi operation of its kind, the museum said, and was made up of three main installations and dozens of subcamps in southern Poland.

There the Nazis starved, shot and gassed men, women and children, burned their bodies in crematoriums and conducted ghastly medical experiments on adults, twins and dwarfs.

“Never shall I forget the small faces of the children whose bodies I saw transformed into smoke under a silent sky,” author and Auschwitz survivor Elie Wiesel wrote in his book “Night.” “So many crazed men . . . so much brutality.”

The Nazis filled warehouses with their victims’ clothing, eyeglasses and hair, among other things. And as the Soviet army closed in, they drove thousands of the remaining prisoners on death marches to other camps.

The Auschwitz complex operated from the spring of 1940 until the winter of 1945, about three months before the war ended in Europe.

About 1.3 million people were sent to Auschwitz during the war, and the Soviets found about 7,000 sick and dying prisoners, the museum said. Overall, 6 million Jews were murdered in the Holocaust.

“As a survivor and witness, I think it’s my personal obligation to speak up to anybody who wants to listen,” Fenves said.

He said he was worried about the extremism and anti-Semitism finding expression around the world.

“Had I given this talk 20 years ago, I would have been much more positive and optimistic than I can be today,” he said. “Today, we are closer to the spirit of the 1930s than the 1990s.”

When Birn, the cellist, who lives in Bethesda, Md., finished playing, she carefully laid down her instrument, which she has had since she was 11. She went to light a candle herself.

She was a little girl, born in Paris, when the Germans conquered France, and with her family managed to elude Hitler’s henchmen. “We were hiding,” she said.

“We were first in Paris, then we fled,” she said. “My parents were arrested. And, miracle after miracle, we were not put in a camp.”

Other members of her family were not so fortunate. “So much of my family, so many members, were murdered in Auschwitz,” she said. “It’s very painful for me.”

She went on: “Two hundred members of my extended family were murdered. It’s a horrible background that I have. I have no family.”

Grandmother, uncles, cousins.

“They were all murdered,” she said.