On Feb. 16, 1939, Szilard’s residence permit as a Czech national expires, and they make plans to decamp for his homeland and await visas there. Meanwhile he applies for a transit camp in England en route to America, noting his high school training in economics and metals and fluency in German, English, French, Polish, Hungarian and Hebrew. But nothing is happening.  Amid frantic efforts for a hearing, they unleash a final burst of letters to the Hilfsverein until the answer comes on April 3, 1939: “We are fundamentally not in a position to provide subsidies for passage to the U.S.A. …” Whereupon the file ends. (I recently donated the originals to the United States Holocaust Memorial Museum in Washington.)  As a war baby, born in New York a month before Pearl Harbor, I sensed a world of danger in whispered conversations and screaming headlines I couldn’t read. My younger sister and I were especially spooked by a black lacquer wardrobe in a dark hallway of our apartment that secreted, or so I remember, orphaned belongings that Szilard and Hella had shipped ahead, intending to follow. Somehow, we had beautiful silver napkin rings with Szilard’s monogram. Maybe the letters came from the closet too.  But little of the story came together until much, much later, although I had, over the years, made repeated trips to Berlin. In 2011, I returned to show our two daughters our ancestral city and track down, at long last, a special address.  Güntzelstrasse is a long street, and it seemed as if we walked for miles before finding No. 49 in a pleasant residential neighborhood of shade trees and small shops. We paused outside the entrance to an inner garden court, green and peaceful. So this is where they lived …  I found a custodian sweeping up and asked if by any chance anyone was still there from before the war. He doubted it. But I left him my card.  We were back in New York when I heard from a tenant, Ingrid Broesicke. As the building’s longest occupant (since 1948 when she was 8, as I later learned), she emailed to say my family story would be of great interest, as she was a nurse who did “remembrance work.” Was I looking into Stolpersteine?  But days later she had bad news. “Unfortunately, it has not been possible to clarify the fate of your uncle.” German federal archives had no record that my uncle had ever lived there.  That was crazy. All the letters I had were return-addressed to him there.  Now, finally, I began a more systematic inquiry. The Central Database of Shoah Victims’ Names, a project of Yad Vashem, the World Holocaust Remembrance Center in Jerusalem, had two testimonials, filed decades apart by Hella’s two sisters in Israel. Unfortunately their accounts conflicted, putting Szilard’s death in Bergen-Belsen in Germany in 1943 or in Majdanek in Poland in April 1942. The sisters had died.  The United States Holocaust Memorial Museum’s collection of the International Tracing Service in Bad Arolsen, Germany, yielded a startling twist. After nearly half a century had passed, someone had asked the Red Cross for further information on Szilard. The inquiry had turned up a list of Jews aboard Transport II from Nitra, Slovakia, toward Lublin, Poland, on April 15, 1942. Szilard and Hella appeared as numbers 729 and 730.  According to an Israeli historian, Yehoshua Buechler, writing in “Holocaust and Genocide Studies” in 1991, Slovakia was one of the first of Nazi Germany’s satellite states to deport Jews to death camps. From March 26 to Oct. 20, 1942, almost 58,000 Jews were put aboard 57 trains, 19 sent north to Auschwitz and the rest beyond to the Lublin district, including Majdanek. Few survived.  Astonishingly, the Red Cross file revealed, the person requesting the information in 1991 was none other than Hella — now Helena Tirkel of Armadale, Victoria, Australia. Four days after she and Szilard had been put aboard the deportation train, they were separated in Lublin. I had known she survived, but no details.  Searching her listed address on the internet turned up a phone number. Which is how I found relatives I never knew I had — a grandniece of Hella’s in Baltimore, other relatives in Israel, and a stepcousin, my aunt’s adopted son, Andrew Tirkel, who was able to provide a striking new dimension.  Andrew turned out to be a 66-year-old scientist/engineer in East Brighton, Victoria, a beachy suburb of Melbourne, with affiliations at Monash University in Melbourne and the University of Adelaide.  By Skype and email, he told me that his parents, Alfred and Sonia, had survived the Holocaust by fleeing east to Kazakhstan; after the war, they returned to Poland, where Andrew was born in 1949. Three weeks later his mother died in botched surgery. When Andrew was 3, friends introduced his widowed father to Hella, who had turned up alive in Warsaw. She moved in with them in 1952; the couple married in 1955 and in 1960 won permission to emigrate, reaching Australia via Switzerland. Alfred died eight years later, widowing Hella once again.  And now? Hella was dead, Andrew told me. She had died at 89 in 1997. She had been his stepmother for 45 years.  I felt sick. I knew that my parents and grandmother had been in touch with her but I had stupidly never sought details. I’d had Szilard’s letters since 1984. In all that time, I could have reached out to her, or even met her.  She had never confided much, Andrew said. What he knew he had gleaned from records and her occasional stories. Once in 1992, he accompanied her on a return visit to Katowice, Poland. They were caught in a traffic jam, and Hella freaked out, flashing back to the railway station and a train to Auschwitz.  Then a Polish researcher I had found through the Museum of the History of Polish Jews in Warsaw located Hella’s passport file under the Communist regime. Appealing yet another refusal of her application, in 1957, to emigrate with her new family, Hella said she had been put aboard a boxcar to Auschwitz. They waited 48 hours for a transfer to Sobibor where, of some 5,000 Jews, a hundred were selected for work. She was one of the lucky ones.  Her husband and “son,” she told the authorities, were sent to their deaths in Majdanek. But Hella had no son anyone knew of, although she told Andrew she had once undergone an abortion, forced or otherwise.  Hella went on to say she was transported to Krychow (variously Kirschhof or Griechhof), a labor camp associated with Sobibor, under the command of the notorious Franz Stangl, who later died in prison while serving life for mass murder.  Indeed, Gitta Sereny’s chilling 1974 book on Stangl, “Into That Darkness,” seems to place him in Krychow about the time Hella arrived.  In October 1943, after a spectacular prisoner uprising and mass breakout, Sobibor was shut down, and by her own account, Hella fled “just before liquidation” (the camp’s or hers unclear). Andrew recalled that she sometimes said she escaped hidden in a hay wagon.  From medical records Andrew remembered seeing, Hella turned up during the war emaciated and badly beaten at the office of a woman doctor in Warsaw who, at great personal risk, nursed her back to health. But a taxi driver stole her last 500 zlotys.  She then became, her Polish passport file shows, “Maria Sowiak,” an ostensible Catholic who survived the war with fake papers in Warsaw — perhaps, from hints she later dropped, working in a sewing factory. Perhaps, too, she was aided by the Polish Underground, which a scholar at Yeshiva University, Joshua D. Zimmerman, suggests in a recent book was not universally anti-Semitic as often portrayed.  Andrew said that after the war he often delivered Hella’s baked pastries to a Warsaw cafe run by Jan Mazurkiewicz, known as Radoslaw, an anti-Nazi resistance hero of the Warsaw uprising and former colonel in the Polish Home Army. For years, too, Andrew later mailed packages from Hella in Australia to mysterious benefactors in Poland.  After liberation in 1945, a government certificate shows, “Maria Sowiak” became “Director of the Trade Centre of Central Management of the Yeast Industry,” commended for “ensuring efficient and timely distribution of yeast throughout the country” and discharging her duties “with great initiative, enthusiasm and sacrifice.”  By 1951, a letter shows, she was Director in the National Directorate of Spas, traveling the country but soon quitting to move in with Alfred Tirkel and resume her real identity to mother her new baby stepson, Andrew. She later learned that her mother had been killed in Auschwitz and her brother Heniak murdered by Nazis on the street in Poland.  As we were leaving Hotel-Pension Funk for the Stolpersteine ceremony, Ingrid Broesicke emailed from Güntzelstrasse. Would we ring her bell when we arrived? She knew we were coming, she said, from the notice posted in the building. Oh yes, she said, the tenants are always notified.  We hugged like old friends, and Ingrid ushered us into her handsome, book-lined apartment, inviting my incessant questions. The building had suffered only scars in the bombardment of Berlin. She and her mother had survived in another part of the city, her parents having separated in 1942, and moved to Güntzelstrasse in 1948. No Jews were left, but she remembered a married couple there who were still unregenerate Nazis. “Bad people,” she said.  Even as a child, she said, she reacted angrily when her mother and others claimed ignorance of the atrocities. “At least admit,” she now said, “you stood behind the door and made in your pants when they dragged the Jews out.” So years later, herself a mother of a grown son in the restaurant business in United States, she busied herself in “remembrance work,” spending time in Auschwitz working with the Action Reconciliation Service for Peace and now volunteering at a Berlin welcome center for Syrian migrants flooding into Germany.  A devout Christian, she said she was shocked to discover in 2000 that 42 area churches, according to their own archives, had run a wartime forced labor camp using Ukrainian prisoners to tend cemeteries. She and fellow congregants tracked down 10 survivors and raised several million dollars for their support.  She told me she had spent the last few years arguing for Stolpersteine for Szilard and Hella. I had had no idea.  Then it was time. From a shelf in her pantry, Ingrid retrieved a bouquet of white roses and an armful of tea lights. We walked out to find a dozen neighbors gathered at the building entrance.  A few minutes before 2, a van pulled up with Gunter Demnig, a stocky figure in a blue work shirt, vest and safari hat. Carrying tools in a bucket and two shiny new Stolpersteine, he stepped across the sidewalk and with a small electric concrete saw sliced out two cobblestones, smashing them apart with a mallet. He scooped out loose gravel and was about to insert the new stones when I stopped him. I placed two small black and white photos of Szilard and Hella in the excavation.  Ingrid and the other neighbors scattered the white roses and lit the candles. A duo of husband and wife violinists, Daniela Jung of the Bavarian Radio Symphony Orchestra, and Reinhold Wolf of the Deutsche Oper Berlin, set their baby carriage aside and played Mozart.  I came prepared to say a few words about Szilard and Hella but at the last minute revised my remarks to begin with the victims in Paris, massacred the day before. “It didn’t end with the Third Reich,” I managed, quaveringly (This would become even more horrifyingly true after Orlando.)  Ingrid called my attention to an array of other brass-topped stones sunk into the pavement at Güntzelstrasse 49, which she said she went out to polish from time to time. “Twenty-one,” she said. “Your uncle and aunt make 23.”  Correction: June 22, 2016 An earlier version of this article misspelled, at one point, the surname of the longest occupant of Güntzelstrasse 49. As the article correctly notes elsewhere, she is Ingrid Broesicke, not Brosicke.  Ralph Blumenthal, a New York Times reporter from 1964 to 2009, covered West Germany in 1968 and 1969, and has written extensively on Nazi war criminals.  A version of this article appears in print on June 26, 2016, on page TR1 of the New York edition with the headline: A Final Goodbye in Berlin. Order Reprints| Today's Paper|Subscribe
A ceremony in Berlin offers an opportunity to say a final goodbye to two family members caught up in the horrors of the Third Reich.