Freddy was nine when he emerged from the Buchenwald concentration camp in 1945. His parents were missing, and he was lucky to be adopted by a Jewish couple in the United States.
But only now - more than 60 years after the end of World War II - has he found out his mother also survived the camps.
And she too moved to the United States, though neither knew of the other's fate.
Freddy was "less than five when he was taken into the ghetto (in Poland) and when he was separated from his mother and father," said Sallyan Amdur Sack, whose uncle and aunt adopted Freddy and who now works for the International Institute of Jewish Genealogy.
"My aunt and uncle attempted to locate any relatives he might have" after they adopted him in 1949, but in vain, she said. Original enquiries turned up nothing because of confusion over the mother's first names.
Amdur Sack, from Bethesda in the US state of Maryland, uncovered the truth in early May when researching at the Nazi prison camp archives held by the International Tracing Service (ITS) in the central German country town of Bad Arolsen.
"I became nauseous when I realized Freddy's mother had survived. I had to leave (the room) I was going to be sick," she said, adding that the search was now on to track down the mother whom she declined to name as the family had not yet been informed.
Freddy's mother "had remarried and had two more boys. Twins. And she came to the United States in 1949," Amdur Sack said.
"If she's still alive, she would be 93, and the chances are not good that she's alive. Most people who went through the camps don't live to that old age," she said. But there's still a chance Freddy could meet his half-brothers.
Until November, the ITS, a branch of the International Committee of the Red Cross supervised jointly by 11 countries, including Britain, France and the United States, only allowed victims and their relatives to access the files.
Now records have been opened to researchers, including historians and genealogists.
‘Heart and soul'
The case is just one of thousands still handled today by the ITS, which holds the archives of more than 17.5 million people who went through the Nazi forced labour and concentration camp system between 1933 and 1945.
Of the 800 or so requests for information received every month by the ITS, about 10 percent concern the search for missing people, according to Margret Schlenke, head of the tracing section, who has worked there since 1970.
Of these, "about a third can be answered positively - either to confirm a death or to allow people to be brought together, truly a wonderful experience," Schlenke said.
"We all put our heart and soul into our work," she said, adding that just reading the requests for information can be heart-wrenching.
These sometime come in waves, as was the case after German reunification and the end of the Cold war.
"After the fall of the Wall (in 1989), it was like a storm, a lot of people from former East Germany, or eastern Europe, who could not, or dared not write, suddenly started applying for information," she said, adding that some cases remain open for years while every last trail is explored "in true detective fashion".
Many people today also try to find out more about parents who died during the war, or were reluctant to talk about it afterwards.
In one recent case, said Nathalie Letierce-Liebig, responsible for the French research section, a Frenchman sought information about his late father, who had been a prisoner-of-war in Germany. The ITS was able to track down two people in a small German village who still remembered him and who revealed that the father had a relationship with a Russian woman POW who had born him a daughter.
The son "was delighted to find out he had a Russian half-sister and we are now trying to track her down in Russia," said Letierce-Liebig.
Other cases are more tragic.
One woman wrote saying she was given up for adoption as a child in France, where her German-born parents, who had opposed Hitler, fled before being arrested and deported back to Germany.
"She did not know what had become of them," said Letierce-Liebig, who found out they were beheaded.
"When we told the daughter, she was devastated, but she wanted to know what had become of the bodies," she said.
"We found out the bodies had been dissected. I still don't know how to tell her," she added.
For Udo Jost, head of archives, who has worked at the ITS for the past 24 years, "when I feel I'm getting bogged down in routine, all I need do is go and read some of the files.
"It makes me angry, and I get back to work with a vengeance," he said.