UNDATED (CNN) -- When Menachem Bodner was just a young boy, he was freed from Auschwitz concentration camp without his family and with only a few tangible memories.
Decades later, with the help of social media, he has opened up about the painful chapter to find clues about his birth family.
This is Menachem Bodner's earliest memory at just 3-years old. He says, "I remember my mother. What she was wearing a green skirt with white flowers and a white blouse. On the left, there was a bed and my brother was sleeping. I remember I had a brother."
Until a few months ago, Menachem, now 73, had no idea his brother even existed. He was just over 4-years-old when the camp was liberated. In the chaos and confusion, he doesn't remember how he was separated from his brother but he did seek a way out. "I was in the camp," he recalls, "A man came in who was looking for his wife and daughter, I stood before him asked if he would be my father, he picked me up in his hands and took me out of the camp."
His adopted father took him to Israel and named him Menachem. Over the years, his father searched for his adopted son's birth family, without success. Menachem began to wonder if his memories were simply dreams.
Last year, urged by his grandchildren he tried again, by posting the only clues he had on the internet, a photo of himself as a 5-year-old and another he believed was a family photo it was in his pocket the day Auschwitz was liberated.
Genealogist Ayana Kimron responded to his post, took one look and knew it was not his. Why? There was no brother in the photo.
At first, Menachem was crushed. One of the few clues was a false start. But Ayana reminded him, he had another lead: one he would never forget. The numbers are faded, but the Auschwitz ID tattooed on his arm is still visible: A7733. And he is looking for 34, A7734.
Through this number, Kimron discovered Menachem was Eli Gottesman and he did have a brother, an identical twin named Jeno, last seen by allied doctors in Auschwitz. Kimron says, "We know that he was declared healthy on the 9th of February 1945 by medical staff. That is really the last factual reference I have."
Kimron also found other, more disturbing records. Both twins were subjected to experiments by Josef Mengele, the Nazi doctor dubbed the "Angel of Death" for his gruesome experiments on humans, particularly twins.
But perhaps thankfully, Bodner has no memory of that, but has he ever wanted to find out what these tests were that were conducted on him? He says, "Sometimes you don't want to remember."
Together, they set up Facebook page A7734, now viewed more than a million times. The search has been rewarding. Last year he traveled to the small village where he was born, he spoke to neighbors who remembered his family, a doctor, his wife, and their smiling children. "I closed a circle," he explains, "It was just good to know that what I was dreaming was real and not my imagination."
Menachem is still searching for his twin brother. But along the way, he has also found himself.