Johnny Pekats, looking at a historical photo, recalls what he felt and what he saw as the trains pulled into Auschwitz. (Courtesy of Todd Pekats)

Never forget? How could he? Years after the physical scars had healed and Johnny Pekats was a Park Avenue barber taking a little off the top for the likes of Adlai Stevenson and Mario Cuomo, he would still wake up in cold sweats.

He hung up his golden shears. Retired to Florida. “Got out of the cold.”

But still, the nightmares came, and he would see them, again, for the last time: Miriam and Sharon. His mother and 4-year-old sister, the bright-eyed little girl who was “the light” of his life.

Graphic: Millions were killed in six primary extermination camps when the Nazis implemented the "Final Solution." The largest of these was Auschwitz.

[Read: The voices of Auschwitz]

A milestone was marked Tuesday in this Polish city that, during the Nazi occupation, was known by its more infamous German name, Auschwitz. For what organizers expect to be the last time, a large group of survivors — more than 300 — gathered in frigid, snowy weather at the bloodiest site of the Holocaust, where they marked the 70th anniversary of its liberation.

In years past, thousands of survivors faced their demons here. But not Johnny. Not until now. The dignitaries came Tuesday — the presidents, the royalty, of both Hollywood and Europe. But after so many years of refusals, something else drew Johnny Pekats back.

Before he dies, he said, he needed to bring his son here. That, and he needed to say a prayer — here, on this soil — for Miriam and Sharon.

He knew this was going to be tough. But “oh boy, is it.” He entered the camp, walked under a rebuilt replica of that lying old sign — “Arbeit macht frei,” or “Work will set you free” — and something within him suddenly broke.

That haunting moment was back. It is 1943 again. He and his brother are getting off the dank cattle car with Miriam and Sharon. His 36-year-old mother is refusing to give up her small daughter. The two of them are taken away as the terrified brothers stand and watch, gazing upon their mother and sister for the last time.

“Oh, God. Oh, God,” he said, unable to control a rush of tears. “This is where they died. This is where they took them from us. I can see it. I can see it! Why? Because we were Jewish? I still don’t get it. I still don’t get the hate.”

On Tuesday, he stood among a dwindling number of survivors — 1,500 returned for the 60th anniversary in 2005 — who sought a measure of catharsis by revisiting this place, where a partially reconstructed gas chamber and crematorium still stand among the brick housing blocks for prisoners.

This year, the landmark anniversary came at an uneasy moment for Europe — particularly for Europe’s Jews.

Attending on Tuesday was French President François Hollande, whose nation is still mourning a wave of terrorism this month that included an assault on a kosher market that left four Jewish shoppers dead. He joined dignitaries including German President Joachim Gauck, U.S. Treasury Secretary Jack Lew and representatives from 46 other state delegations in honoring survivors through commemorations held in and around the railway entrance to the Birkenau section of the camp, known as the Gate of Death.

Notably missing was Russian President Vladimir Putin, who complained that he wasn’t invited, though organizers said no leader got a formal invitation. Putin’s absence this year, after he attended in 2005, appeared to speak more about Moscow’s deteriorating relationship with the West, and Poland in particular.

Under a massive white tent, a documentary produced by Steven Spielberg — who sat in the audience — illustrated the military efficiency of the Nazi camps that became an assembly line of death. During a series of speeches, one Polish survivor, Roman Kent, described his imprisonment as an eternity spent among madness. He spoke of lessons unlearned in the decades since, noting the genocides in Rwanda and Darfur. The commemorations harbored strong references to the here and now, including the rise of anti-Semitism in nations including France and Hungary.

“We survivors do not want our past to be our children’s future,” Kent said.

Walking through the camps

A day earlier, survivors also toured the camps — including a handful who, like Pekats, had never returned before. This is an important year, said David Dario Gabbai, a 93-year-old survivor who traveled to Poland this week from his home in California. By the next major anniversary, he said, “time will have exterminated almost all of us.”

And that’s why, at 85, Johnny Pekats finally came back.

The retired barber walked the cellblocks of Auschwitz on Monday morning, arm in arm with Todd Pekats, his 49-year-old son, a technology executive who Johnny, in his Eastern Europe-meets-Manhattan accent, calls “the smartest guy around.” Yet, on this one doozy of a subject, he had always found it easier to communicate with his daughter, Marcy Pekats Bratman.

“When I was 13, 14, he would bring it up, but I think he would get frustrated because I wouldn’t respond the way he wanted,” Todd Pekats said. “He took that to mean that I didn’t care, that I wasn’t interested. The truth is I cared too much to really process it.”

‘Leave your children’

Johnny Pekats’s most vivid memory is getting off the train. Someone was calling out, “Leave your children, leave your children,” he said. “And I thought, ‘What, leave your children? That can’t be.’ ” Instead, he tightened the grip he had on his sister’s hand. But as they approached the Nazi with the stick in his hand, the one who separated those who could work from those who could not, his mother turned to him.

“ ‘Let me take her,’ ” he recalls her saying. “ ‘You go with your brother.’ ” Hours later, others in the camp told him what had surely become of them. “You could smell it, the death coming from the chimneys. It was horrible,” Pekats said. “They told us — I was 14 — and they told us, ‘Your mother is not coming back.’ ”

He paused before the darkened entrance to a gas chamber and crematorium at Auschwitz, as if unable, at first, to go in. Then, clutching his son tightly, he stepped through.

He stopped in front of the furnace, at first not really registering the device before him. His eyes went wide, and then another flood of tears. He has kept a portrait of his mother under his pillow, sleeping with it, he said, every night for decades. “My mother, my mother. My little sister,” he said, unable, for several moments, to say more.

His son, who both men said had never before wept over his father’s ordeal, suddenly broke down, too.

Supporting each other, they left the darkened chamber, stepping together into the light of day.

“This is terrible,” Johnny Pekats later said of returning. “Terrible. Terrible. But I have my son here, and he sees, now he sees, with his own eyes. He sees what happened. He will tell his children. And they will tell theirs.”

Stephanie Kirchner in Berlin contributed to this report.