Eva Kor survived the twin experiments at Auschwitz. Last week, she died nearby.

There’s a photograph taken on January 27, 1945, the day Auschwitz was liberated. Thirteen children, some wrapped in oversized striped prison shirts, stand huddled together behind barbed wire. These thirteen were among just 7000 survivors of the lethal concentration camp. Seven thousand of the estimated 1.3 million people that had been sent there to die during the course of the Second World War.

In that photograph, second from the right, is Eva Kor. A woman who devoted the past four decades to sharing the stories of those who perished during the Holocaust and to advocate for forgiveness as a path to healing.

As well as writing a book, Echoes of The Holocaust, and appearing in media and documentaries, each year she led tours of the camp that stole her adolescence.

She was conducting one of those tours when she passed away on Thursday, aged 85.

The CANDLES Holocaust Museum and Education Center, which Eva founded in the US state of Indiana, shared that Eva died in a hotel room in Krakow, near the camp.

“Surviving the Holocaust at age 10 meant that Eva emerged from a childhood full of fear, loss, grief, and displacement,” the museum said in a statement. “But rather than allowing the darkest moments of her life to define her, she moved forward headfirst into a life of purpose.”

Eva was born into a Jewish farming family in Romania in 1934.

When the Transylvania region fell to German occupation late in WWII, they were among thousands sent to Auschwitz-Birkenau.

There, Eva's parents, brother and two of her sisters were led to their deaths in gas chambers. But she and her sister, Miriam, were spared the same fate by virtue of their relationship: they were twins.

Some 1500 twins were subjected to horrifying experiments by Nazi eugenicist, Dr Josef Mengele (known to history as "The Angel of Death"), who believed that studying them could advance Adolf Hitler's pursuit of creating an Aryan master race.

Recounting her experience of Auschwitz for The Forgiveness Project, Eva wrote, "Miriam and I were part of a group of children who were alive for one reason only — to be used as human guinea pigs.

“Three times a week we’d be placed naked in a room, for six to eight hours, to be measured and studied. It was unbelievably demeaning."

Blood was drawn, and germs injected into their arms to see how their bodies would respond.

"During our time in Auschwitz we talked very little," she wrote. "Starved for food and human kindness, it took every ounce of strength just to stay alive."

Though both survived, the experiments caused irreversible damage to Miriam's kidneys, and she passed away from complications in 1993.

'Society expects revenge.'

After the war, Eva moved to Israel and then began a new life in the United States. After seeing a documentary about the Holocaust in 1978, she began opening up about her experience and launched an organisation to unite twins who'd survived Mengele's experiments.

She also connected with Nazi doctor Hans Münch, who agreed to travel with her to Auschwitz and sign a letter acknowledging the existence of the gas chambers and the horrors committed within. Together on the 50th anniversary of the camp's liberation in 1995, they stood side-by-side as he put pen to paper. Eva signed a letter of her own; one of forgiveness for Mengele and the Nazis.

"For most people there is a big obstacle to forgiveness because society expects revenge," she wrote in her Forgiveness Project essay.

"Some survivors do not want to let go of the pain. They call me a traitor and accuse me of talking in their name. I have never done this. I do it for myself. I do it not because they deserve it, but because I deserve it."

It's a message that Eva's 58-year-old son, Alex, hopes to continue to spread. Posting to social media in the wake of his mother's death, he wrote:

"At some point, I will indeed try to continue my mother’s life work. There is definitely unfinished business. Like my mother, I want my life to count for something.

"Moreover, from her perch in heaven, as she eats a few more McNuggets while chatting with my aunt, Miriam, she will say: '… Hi Sweetie. You are doing great. I love you, too...'"