OSWIECIM, Poland -- The Russians freed Judith Rosenbaum a half century ago, sticking their heads into the room of an Auschwitz-Birkenau barracks where she and Ruthie, 10-year-old twins, lay sick.


Judith came back Friday, for the first time since that cold winter's day.


And she found what she came for -- the common grave bearing the remains of Ruthie, and about 300 others for whom liberation came too late.


"Today, I got to the exact place," said Rosenbaum, snow swirling around her in a bitter wind as she stood with other Auschwitz survivors who came from Israel for official observances of the Nazi death camp's liberation. "I have closed the circle now. I don't know if I could come back."


Ruthie died on March 30, 1945, mainly of tuberculosis.


Judith and Ruthie were "Mengele twins." They were spared immediate death in the gas chamber, when they arrived with a trainload of Hungarian Jews in 1944, so that Dr. Josef Mengele could experiment on them.


"My father was immediately taken to the gas chambers," Rosenbaum said dispassionately, refusing to allow emotion to take over.


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"When we arrived at Auschwitz, there were young Polish women who were already here four years at least, and they were very, very cruel," said Rosenbaum, her 24-year-old son standing by silently.


"They told my mother, 'You know what these flames are? All your family, your husband, everyone,'" she said. "We could see the flames coming out of the crematorium and smell the smoke."


Mengele personally selected his specimens and tried to persuade Rosenbaum's mother that her twins were members of the "master race."


"Mengele said, 'You cannot have those children if you have no Aryan blood in your family,' ... because we were very beautiful children."


The Rosenbaum twins were spared the maiming Mengele inflicted on others -- who were routinely killed when he finished.


"There was no time," said Rosenbaum, a handsome black-haired woman. "That was our luck." Their mother kept them alive, clearing barracks of human excrement and, in return, getting a few extra scraps of potatoes for her girls. "I think that is the main reason that I am alive today," Rosenbaum said.


But at the end of September, after the SS had slaughtered the last of some 21,000 Gypsies, the Mengele twins were sent one night to the emptied Gypsy barracks and stood outside an entire freezing night.


Ruthie's feet got frostbite and some of her toes had to be amputated.


"That was the beginning of the end," said Rosenbaum, who left the Red Cross Hospital at Auschwitz with her mother a few days after Ruthie died.