THE BOY WHO HAD TWO LIVES

IN THE course of researching the story that follows I talked to Steven Spielberg, who made the film Schindler's List. Like Schindler's Ark, the novel on which it is based, the film used fictional devices, invented scenes and dialogue to dramatise fact. The film was such a success that it would be fair to say that many millions of people received their primary instruction on the Holocaust through it. Spielberg diverted much of the profits from the film into another of his creations, the Shoah Foundation, which would record the memories of the Holocaust's real survivors - people delivering their witness accounts to camera, the only script their own. The Shoah Foundation has done remarkable work. In Spielberg's words: "We have collected more than 50,000 testimonies in 31 languages across 57 countries. That's more than 14 years of material [in playing time], enough videotape to circumnavigate the globe." The question I wanted to ask Spielberg was an uncomfortable one: would this great archive serve the future as a reliable source of history? "Absolutely," said Spielberg. "Through the material, long after they are gone, survivors can speak to the future generations."

To break our trust in these memories would be a cruel thing; to question their veracity, equally cruel.

I look at the picture reproduced here - that nice-looking, sensitive boy - and wonder, not for the first time, where he thinks he has come from and who he thinks he is.

MORE THAN half a century ago, soon after the end of the Second World War, a young boy became the foster child of Dr Kurt and Mrs Martha Dossekker, wealthy, German-speaking Swiss citizens. The couple had no children of their own and no prospect of having any; Mrs Dossekker was nearly 50, her husband several years older. They had high hopes for their foster son. Perhaps he would become a successful physician and perpetuate the family's name.

The child arrived, according to all the available documentation, with the name of Bruno Grosjean. He was born in the Swiss town of Biel, and had been taken into care by the authorities, since his mother was poor and he was illegitimate. In 1947, the year he started school, his adoptive parents changed his last name to Dossekker.

Bruno Dossekker was in some ways a disappointment to his new parents. At school, he took more interest in the arts than in sciences. At university in Geneva, he abandoned a course in medicine and turned instead to history and music. He became a clarinet player and teacher, and also a clarinet builder. In 1964, when he was 23, Bruno married a Zurich girl, Annette, and they had three children. But the marriage became strained and he and his wife separated. In 1981 he fell seriously ill. A year later, he met his new partner, Verena, an opera singer who taught music at the same school as Bruno. Together they moved to a farmhouse in the country and slowly Bruno began to regain his health.

It was at about this time that he began to write down scenes from his early childhood. These were not scenes from a Christian childhood in Switzerland, but from a Jewish childhood spent in the most terrible time and place to be Jewish in modern history. He remembered being a Jewish child in Poland during the Second World War, and he remembered the horrors he had endured, separated from his parents at the age of three, in the Nazi concentration camps.

He could recall these experiences with such extreme emotional clarity that, encouraged by Verena, he eventually turned them into a book. The book quickly found an agent, the agent found a publisher, and then many publishers. It appeared first in Germany in 1995, and soon after in another dozen countries. It was widely praised and won literary awards. Publishers and critics talked of it as a "classic" of Holocaust literature. Its author appeared in documentary films and began to address conferences and seminars on the Holocaust. In the English translation, its title is Fragments: Memories of a Childhood, 1939-1948.

Fragments told the powerful story of how the author was separated from his parents during the massacre of Jews in Riga, how he escaped by boat to Poland, how he was taken to Majdanek concentration camp and then to another camp, possibly Auschwitz; how at the end of the war he was taken to a Jewish orphanage in Cracow, and then, when he was about seven, to Switzerland; and how his adoptive parents and Swiss society in general had repressed these memories by refusing to acknowledge them.

Both his adoptive parents died in 1986, which, given the book's unsympathetic portrayal of them, might have been just as well. In any case, Bruno Dossekker was no longer the author's name. Some years before, in the 1980s, he had begun to call himself Binjamin Wilkomirski. The name "Dossekker" appeared nowhere in his book.

I FIRST MET Binjamin Wilkomirski in the spring of 1997, when he came to London to receive the Jewish Quarterly prize for non-fiction. I was editor of that magazine, and when I met Wilkomirski at the awards ceremony, I thought: Here, for the first time in my life, I see a writer who actually is his book. But he hardly seemed old enough or strong enough to have survived the Holocaust. He had a slight body and a soft face framed by sideburns and a halo of light-brown curls. I tried to congratulate him and talk a little about Fragments, but he managed only a weak smile. When he did speak he wept. He was visibly moved by everyone's response to what he had written.

I had read his book as the terrifyingly stark testimony of a man whose identity had been shattered even before he had a chance to become a child. "I have no mother tongue, nor a father tongue either," the book begins. "My language has its roots in the Yiddish of my eldest brother, Mordechai, overlaid with the Babel-babble of an assortment of children's barracks in the Nazis' death camps in Poland."

It seemed that no one - no prize judge, publisher, critic, scholar or reader - was troubled by the author's two-page afterword in which he shyly introduced the idea to his readers that Binjamin Wilkomirski was not his only identity. Like many child survivors of the Holocaust, he wrote, he had received a new identity, "another name, another date and place of birth". But it was merely a piece of paper - "a makeshift summary, no actual birth certificate" - which gave the date of his birth as 12 February 1941. "But this date has nothing to do with either the history of this century or my personal history. I have now taken legal steps to have this imposed identity annulled." He went on: "Legally accredited truth is one thing - the truth of a life another. Years of research, many journeys back to the places where I remember things happened, and countless conversations with specialists and historians have helped me to clarify many previously inexplicable shreds of memory ..."

Looking back, I can't say that my feeling towards his book could be defined as "suspicious" - I too had read the afterword without a qualm - but I was struck by how well constructed it seemed, that it wasn't fragmented enough, despite its author's claim that he had not imposed an adult perspective on his child's view. But the idea that the book could be a confection, that Wilkomirski had been nowhere near the Holocaust, did not occur to me until a Swiss weekly, Weltwoche, published two pieces in August and September 1998, by Daniel Ganzfried, a young Swiss Jew and, like Wilkomirski, the author of a book set during the Holocaust. Ganzfried denounced Fragments as a work of fiction. He wrote that Wilkomirski's true biography would exclude the possibility of his ever having been in a concentration camp, "except as a tourist". Ganzfried supplied documentary evidence to show Wilkomirski's childhood had been spent in peaceful, neutral Switzerland, and his expose was picked up by the media. Taken at face value, it seemed to reveal Wilkomirski as a fantasist and his book as a lie. But Wilkomirski's several publishers did not drop the book from their lists; apparently, they were not convinced. As for Wilkomirski, he refused to respond to his accuser, other than to say in an interview soon after Ganzfried's piece appeared that his readers had always had the option to understand his book as either fact or fiction. He then withdrew from public life, on his doctor's advice.

Still, I wondered if he would see me. We had met before, I was hardly an enemy. In fact - a confession - whether or not his book was a lie, I felt sympathy for him. He had seemed so fragile, and why invent such a terrible childhood? His reply to my request was filled with rage against journalists. But nevertheless he agreed that we could talk. He would pick me up at Weinfelden station, about an hour from Zurich, and from there drive to his farmhouse.

THE EARLY morning train from Zurich moved through hills and fields which were white with snow. I thought about Wilkomirski. Did it matter so much whether Fragments was fact or fiction? Wasn't it enough that its prose was so moving and powerful that it made hundreds of thousands of readers think about and perhaps feel - if not understand - the Holocaust? But I decided that these defences would not do. If Wilkomirski had made it up, his pretence as a genuine survivor, his public speeches in the name of all child survivors, his book's role in the historical record - all these needed to be denounced. If care with the truth does not matter here, then it can matter nowhere. Then again, if Binjamin Wilkomirski had not, as a small boy, lost his family to the Nazis; if he had not witnessed unimaginable suffering and survived; if inside this man was not the little boy who remembered such horrors that he had to forget them before he could remember them again - then another question of truth arose: what had happened to him, who was he?

When I walked from the platform I saw him across the station car park. He was thinner than I had remembered. As I approached him, I realised that I had kept only a blurred picture of him in my memory. Now I saw a face I would no longer describe as soft. It was a busy, attractive face.

He barely smiled as we shook hands. I worried about his nervous state, but he was a determined, confident driver, negotiating the icy roads at higher speed than I thought necessary. He talked in a low voice in slightly Yiddish-sounding German about the friendliness of his village.

I had imagined his home to be a lonely farmhouse in the countryside, but it stood, majestically, in the centre of the village. I liked it; it was inviting, unpretentious, full of books, papers, photos, paintings. There was a profusion of rather touristy Jewish memorabilia. His partner, Verena, greeted me warmly. She, too, looked much thinner now, and I thought of her sustaining presence everywhere he went - all his journeys, interviews, parties, public events. I knew that she had a handicapped son, and that her life had not been easy, even before she met Wilkomirski. In one of the documentary films made about him, she says: "I call him Bruno. 'Binjamin' has something diminutive about it, like being the youngest son, and I don't want to see him in that way. In spite of all the suffering, life has moved on, even his life."

It was 10am when we started talking, and we didn't finish until almost six that evening. Wilkomirski didn't want me to use my tape recorder or my camera. "There have been too many pictures of him already," Verena said. "Every article comes with a huge portrait of Bruno. It's ridiculous!"

I wondered if I could see his Holocaust library, a personal archive of papers, books (2,000 of them), films and photos. Wilkomirski shook his head; "I don't have the strength for all that at the moment. Maybe I'll go back to it when I'm better, but now ... I'm very weak." His voice was a boy's soprano, a little on the feeble side. It occurred to me that it was much easier to tell the story of a traumatic childhood in that delivery, rather than an adult baritone. It was a child's voice and it was asking for gentle, considerate treatment.

After a few remarks about the viciousness of the press, he relaxed a little and began to talk about his work. He teaches music at three schools, and has a workshop where he builds his clarinets. Then, although he wouldn't show me the archive, he talked about what it meant to him. With the help of a computer technician, he examined documents and photographs which related to children who had been given new identities. "I have been in contact with many people who are in that situation. I try to help them."

"Last time we saw each other you seemed very happy."

"Happy ... that would be the wrong word, but I was pleased that my book had helped people, and that I was receiving so much moral support. I felt that I could come out of my hiding place, and could really be myself. For the first time in my life, I felt liberated."

"And now?"

He fell silent for a moment.

"Now I feel like I'm back in the camps."

The Holocaust had entered our conversation and now didn't leave it. He avoided trains, he said, because he could not forget those trains. "When I was married to my ex-wife and had to commute to Geneva for a while, I pretended to take a train ... but secretly I always took the car."

"Can I tell about the feet?" asked Verena. He nodded.

"Bruno moves his feet constantly during his sleep. It's a habit he's had since the camps, to keep the rats away at night."

"Yes," Wilkomirski said, "if you keep moving them, like this" - he demonstrated a waving motion with his feet - "the rats stay away."

When he talked about the camps, he trembled and cried. Sometimes, he couldn't speak and needed to wait before he caught his breath again.

Later we switched to a less sensitive topic: Switzerland.

"In this country, everything and everyone had to be proper, quiet, bourgeois ... That is how I was brought up, and I played along I guess. But in 1981, when I recovered from my illness, which had almost killed me, I said to myself: 'I am sick of leading this pretend-Swiss life. Enough of all that.' And I decided to be myself, which meant going back to the beginning - my own beginnings."

Ten difficult years followed. He continued to be ill: a disease of the blood cells. It was Verena - after he met her in 1982 - who suggested a connection between his physical state and his mental anguish. "She was the first person who was willing to listen to me, really listen." He began telling her what he remembered. In about 1990 she advised him to start writing his memories down. She also recommended a therapist, who was a friend of hers.

Wilkomirski said: "The idea of the therapy was for me to learn to speak about my past without fear or panic. It also helped me to clarify certain details of my memories."

I turned to Verena: "Did you always believe him?"

"Not always. I had my doubts. But the more I listened, the more I was convinced, because his stories were always consistent. And his research, when he travelled to the places where he thought his memories belonged, finally confirmed so many things - I have no doubt that he is telling the truth about himself. I checked the papers as well."

Before he drove me to the train, Wilkomirski took me to the barn and showed me his music room and workshop, where, to my surprise, he agreed to pose for a picture.

On the train back to Zurich, my head throbbed from all the talk. I believed him. Whenever he talked about the camps, I believed him. His anguish was so genuine. It was impossible that someone could fabricate such suffering simply to justify the claim of a book. I returned to my hotel exhausted, and convinced that I had been in the presence of a witness to some of the worst horrors of this century.

WILKOMIRSKI'S main accuser, Daniel Ganzfried, was assigned to write about him by a magazine called Passages, for an issue featuring "creative people who excelled in an area which was different from their daily job". Wilkomirski, as musician-cum-writer, was an ideal subject. Ganzfried interviewed him, and then told Passages that his account did not seem credible. According to documents Ganzfried had found, Binjamin Wilkomirski was born Bruno Grosjean in Biel on 12 February 1941, to Yvonne Grosjean, who was unmarried; placed in the care of the Biel welfare authorities; taken by the Dossekkers as their foster son from a children's home in Adelboden, and brought to Zurich in 1945. He was registered as starting school in Zurich in 1947 and legally adopted by the Dossekkers on 4 October 1957. The "makeshift summary" which Wilkomirski refers to in his afterword is one of these documents. Wilkomirski is right - it is "no birth certificate", in the sense that it wasn't issued at the time of his birth and omits information (the father's name, for example) normally found on birth certificates. It is headed "summarised birth certificate". But it hardly looks "makeshift"; it contains the names of his mother and his adoptive parents, his place and time of birth, the stamp and signature of Biel's registrar.

Ganzfried's story began to turn into a piece of detective work. The research needed money, and Weltwoche, Switzerland's leading cultural weekly, stepped in as joint funder. Then, when the piece was finished, Passages turned it down because: "We had been looking for a sophisticated portrait of the writer Wilkomirski, not a character assassination." The people at Weltwoche on the other hand, were delighted. Ludwig Hasler, the paper's literary editor, who worked closely with Ganzfried on the piece, said: "The only way to deal with the Holocaust is to study it rationally ... I despise every sort of exploitation of the Holocaust, which is exactly what Wilkomirski has done."

Ganzfried's demolition of Wilkomirski relied on more than the archives. He had also discovered that Yvonne Grosjean's brother (Bruno's uncle) was still alive; and that Bruno's natural father had paid towards the cost of his son's care until he was legally adopted in 1957. Ganzfried had asked Wilkomirski whether he was circumcised, which he said he was, and Ganzfried even went so far as to ask a former girlfriend of Wilkomirski and his former wife whether or not he was. Both said he was not.

None of this changed Wilkomirski's position, which was (and is) that whoever Bruno Grosjean may have been, he, Wilkomirski, was and is not him. He thinks that the Dossekkers must have used Bruno Grosjean's papers in place of his own, possibly non-existent ones. He believes that such cases of false identities were quite common in post-war Switzerland, and speaks of a "conspiracy" between "the Swiss authorities and private individuals". He has no evidence to support his claims, "except for my memories".

So what became of the "real" Bruno Grosjean? Wilkomirski told me that the Dossekkers took in another child before him. He remembers discovering a room full of old toys in their house, which was quickly emptied when he mentioned it to his adoptive mother. The toys, he believes, may have belonged to the real Bruno, whose name and papers Wilkomirski was then given. Where did the real Bruno go? Wilkomirski remembers that when he was a teenager in Zurich he once met a boy of about the same age ("His name was Rolf or something like that") who told him that he was pleased to have escaped being raised by the Dossekkers, and that he was emigrating with his family to the US.

IN HIS afterword, Wilkomirski writes that he was one of "several hundred children who survived the Shoah ... lacking any certain information about their origins, with all traces carefully erased, furnished with false names and often with false papers too. They grew up with a pseudo-identity which in Eastern Europe protected them from discrimination, and in Western Europe, from being sent back East as stateless persons." A number of Jewish children did survive the Second World War in Eastern Europe, hiding with Christian families or in convents and monasteries. After the war, some of them could not, or did not wish to, find their way back to their origins. In the course of researching this story, I got to know several people of Wilkomirski's age or older with origins in Eastern Europe who have changed their names (or had their names changed for them), sometimes more than once. And it is also true that in Switzerland children have had their identities changed for other reasons, not connected to the Second World War or Jewishness. From the 1920s until the 1970s, a welfare organisation called Pro Juventure campaigned to have children of Swiss gypsies removed from the country's streets, which sometimes meant that these children were separated from their parents and given new names.

Wilkomirski mentioned the fate of Swiss gypsy children to me, as a demonstration of what the Swiss state was once capable of; how it could at least acquiesce in the matter of forged identity. The combination - a secretive state with dubious wartime sympathies, a child victim of the Holocaust in its midst - is plausible, and when I talked to Thomas Sparr at Suhrkamp, publishers of Wilkomirski's book, he was happy to take it into account, before offering his own hypothesis: "Maybe he met young Jewish survivors in his orphanage in Switzerland, and somehow absorbed or was influenced by their stories." Sparr said this late in 1998. In 1994, however, he had believed Wilkomirski's explanation ("His book had to be true; we would not have published it as fiction"). I asked Sparr if he now thought he should have done more checking. He himself is a scholar of Jewish literature and history. Sparr said that he and his colleagues had approached one other person for her historical authority: Lea Balint, director of an organisation called the Bureau of Children Without Identity in Israel. Balint, herself born in Poland, confirmed that there was no doubt that Wilkomirski had been a child in the Cracow orphanage - he had remembered people and details which he could not have known otherwise.

Lea Balint was keen to speak to me - "anything to help Bruno". She is Wilkomirski's most outspoken defender, and has absolute faith in the truth of his story. She is portly and energetic and refers tenderly to the adults who lost their identities in childhood as "my children". She herself spent the war under an assumed name in a Polish convent; and whatever her qualities as a scholar, her emotional involvement and compassion are beyond doubt. She keeps her database - long lists of children who were found in Poland after the war - in her basement.

Balint showed me how the database works. She matched the name of a child on one list with a different name but perhaps similar information (date and/or place of birth, parents' names and so on) on another. Clues are yielded. Identities take shape. Her methods have had only limited success, but with every success story Balint feels almost as though she has saved a life.

She met Wilkomirski in October 1993, four months before he delivered his manuscript. He was introduced to her as "Bruno", the name she still calls him by, at a conference of child survivors in Israel. Wilkomirski told Balint what he remembered: street names in Cracow, an orphanage there, a few other details. "He also told me the name of a woman he remembered from the orphanage."

"A woman?"

"A girl, older than him, who looked after him for a while. Later, we found her name in the lists."

"Where is she now?"

"I cannot say, because she cannot talk about the past. That is her right."

"Did she remember him?"

"No, she did not remember him."

Lea Balint was so convinced by Wilkomirski's memories of Cracow that she invited him to join an Israeli television crew, which was researching children with lost identities. Wilkomirski's appearance in the documentary as a visibly tormented man, searching for his identity in the streets of Cracow, attracted some attention when it was broadcast on Israeli television in November 1994. In addition to shots of Wilkomirski identifying a building which he believed had been his orphanage (it wasn't), there was amateur video footage showing him in the Majdanek concentration camp, recognising the scene of his memories.

Balint told me that Wilkomirski was able to find the real "Frau Grosz", the woman who took him from Cracow to Switzerland, after the film was shown: "We were contacted by a woman from New York, who said that she had been at the same orphanage, and that her mother, who was no longer alive, had often been there. Her maiden name - and her mother's last name - was Gross."

This information has often been cited by Wilkomirski, by Lea Balint, and by Suhrkamp in defence of the book's authenticity. But when I telephoned the woman in New York she told me a less simple version of the story. Mrs Sara Geneslaw was nine years old when she was in the Cracow orphanage. She said that, yes, Wilkomirski's description of "Frau Grosz" had reminded her of her mother: "She would have been likely to talk gently to a child, to explain things to him. But I also told him that it would have been utterly impossible for her to leave Poland and travel to Switzerland at the time. Nevertheless, he asked me to send him a photo of my mother, which I did - one from the late 1940s. When he received it, he phoned me. He was very excited, and said that he definitely recognised her. He asked for my permission to keep the photo beside his bed."

THE FILM had another, dramatic consequence. A woman who saw it was struck by Wilkomirski's resemblance to members of her husband's family and alerted her former brother-in-law, Yaakov Maroco, a Polish Jew who had lost his first wife and two-year-old son in Majdanek. The boy who had perished in Majdanek was also called Binjamin.

Yaakov Maroco was cautious at first, but eventually prepared to welcome Binjamin Wilkomirski into his large family as his long-lost son. They wrote warm letters to each other. Then, before they met, they agreed to have DNA tests which would establish their relationship beyond doubt. The results of the test were clear: there was no way that he and Wilkomirski could be a biological father and son.

Maroco was disappointed, but did not give up. Being an orthodox Jew, he consulted his rabbis, who said that despite the DNA results he could continue to think of Wilkomirski as his son. And so, when Wilkomirski landed at Ben-Gurion airport in April 1995 he was greeted by film crews, reporters and spectators, all come to witness the reunion of father and son. Their emotional embrace was a touching sight - reported in the international press - as though love and mutual affection could defy science.

When I was in Israel in November 1998, Maroco's widow told me that her husband was well aware that Wilkomirski was not his real son. Wilkomirski confirmed this: he said he simply felt very comfortable with the old man, and was grateful for the warm welcome, and for the feeling of having acquired an instant large family.

Other evidence, however, suggests that this isn't the case - that even after the DNA tests Wilkomirski wanted to believe that he had found his father. Maroco's autobiography contains an affectionate letter from Wilkomirski - before they had met. Wilkomirski expresses his joy at receiving a phone call from Maroco, and says: "I have lived for over 50 years without parents, and now - can it be that I have found you, my father? Has 'He' performed a miracle? And think about it: today is February 12th, the anniversary of my arrival in Switzerland, and this day has been made into my official birthday. Is this not a gift?"

He goes on: "I don't really care about the results of scientific blood tests - there are too many connections ... You were also in Majdanek. I have lists of more than a thousand children in Poland, who survived in camps or in hiding, and the name Benjamin [sic] does not appear even once. Maybe it was not such a common name in Poland at that time. It is therefore unlikely that there were two different Benjamins in Majdanek in 1943."

There are several statements to consider in this letter. First, Wilkomirski says that his "official" birthday records the day and month he entered Switzerland; in fact it is Bruno Grosjean's birth-date in Biel. Second, in his eagerness to have Maroco as a father he seems willing to deny his memory as presented in his own book. Maroco lived in Poland; Wilkomirski thinks he grew up in Latvia. Wilkomirski thinks he saw his father killed; and Maroco, of course, was alive.

I MANAGED to trace and talk to several people who had lived in the Cracow orphanage during the period described in Fragments. Not one of them, during our phone conversations, could remember a boy who matched Binjamin's description. One of their carers, Pani Misia, mentioned in Fragments, is still alive. And yet, when Wilkomirski met her in 1994, she did not remember him either.

Can nobody vouch for his presence there? In his book, Wilkomirski suggests that at least one person can.

We come, finally, to the case of the girl "Mila". He devotes an entire chapter to her. She was older than him and gave him "some sense of safety and peace". They had met before "[in] one of the many barracks probably, we weren't sure anymore". In the orphanage, they befriend each other as lonely survivors of the death camps.

Many years later, in Switzerland as adults, Wilkomirski and "Mila" meet again: "We met quite by chance. She was working as a translator, and I'd become a musician. Mila and I saw each other regularly now - we often had long talks. We discussed the present, but what we really meant was our past ... We loved each other, and our love was fed by our sadness. But it was always accompanied by a fear of touching what actually bound us together. So, inevitably, we lost each other again."

Mila was probably a girl who appears in different records as Martha Fligner or Karola Fliegner, born in Lemberg (Lvov) in 1931. The later part of her life story is consistent with Wilkomirski's account. She now lives in Paris but spent some time in Switzerland.

Do I believe Wilkomirski knew her? Yes - in Zurich, when they were adults. But when they were children in Cracow? That seems less likely. Establishing "Mila's" identity has its own difficulties, but it seems that at some point in 1946 she moved to the Augustianska orphanage.

In 1994, Wilkomirski seemed certain that this girl and the woman he knew in Switzerland 20 years later were one and the same. Yet, in a fax to a friend on 8 July that year, he concedes that, according to Red Cross records, she had spent the war in hiding and not (as his book has it) in a camp. What is more, she came to the orphanage only after the time Wilkomirski now implies he was there.

Despite several approaches from me, Mila declined to be interviewed. She is, however, the woman whom Lea Balint told me could "really help Bruno if she could confirm his memories". Sadly, according to Balint, she did not remember him at the Cracow orphanage.

So what role did "Mila" play in the making of Wilkomirski's book? I think this: she was another stage in his exercise of imaginative reconstruction. Perhaps it was from her, when they were both adults in Zurich, that he first heard the story of the orphanage on Augustianska Street.

Wilkomirski wrote in his afterword: "years of research, many journeys back to the places where I remember things happened, and countless conversations with specialists and historians have helped me to clarify many previously inexplicable shreds of memory..." Novelists sometimes take a similar route. They have an idea for a story in a certain place and time; and then, just to make sure no solecisms crop up in the narrative, they might travel to a city to check its streetlife and spend a few days in the local library. Wilkomirski wasn't dealing with a novel, he was dealing with his life; but I began to see how such a process could have led to the writing of Fragments.

In Fragments, he mentioned two teachers who inspired him - a maths teacher, who was Jewish, and a history teacher, who was committed to describing the truth about Nazism. According to another student at the same school, Bruno then was "a very happy adolescent, good-looking, popular with the girls ... his parents let him do whatever he wanted, he skied a lot, was interested in jazz and dancing". But that seems to have been the public Bruno. His drawings and paintings from that time (he showed me examples) suggest a deeply troubled adolescence; a favourite, which he pinned above his bed, is of a dark prison cell.

Wilkomirski often refers to his memories as being filmlike. I think they are more than that: they are, I believe, derived from films. In a documentary about him, he is shown watching concentration-camp scenes on television. His face has the same suffering expression as when he talks about being there himself. Perhaps, in some sense, he is.

And now I consider the main evidence against him. The birth certificate that says he was Bruno Grosjean, born Biel, Switzerland, 12 February 1941; the records which show Bruno Grosjean's adoption by the Dossekkers; the con- tinual revision of his hypothesis; his absence from the memory of anyone who might have known him in Cracow; and, crucially, an unwillingness - as disclosed by Ganzfried and repeated to me - to submit to a DNA test which might prove his relationship to Yvonne Grosjean's brother Max. To take that one step might risk everything.

For all these reasons, I cannot believe that Fragments is anything other than fiction. And yet, when I came back from his farmhouse that evening, I was, as I said, convinced he was genuine. Anguish like his seemed impossible to fabricate. As the Holocaust historian Israel Gutman said to me: "Wilkomirski has written a story which he has experienced deeply, that's for sure."

The question now is: what story and which anguish? According to the archivist in Adelboden, Bruno Grosjean arrived in that Swiss resort as a four-year- old on 20 March 1945. He came from Biel, where he was under the guardianship of one Walter Stauffer, a care-worker. Stauffer and two assistants looked after hundreds of children; in Bruno's case he seems to have acted in loco parentis from the boy's birth in 1941 until his adoption in 1957, when Stauffer signed the adoption papers (he died soon after). At Adelboden, Bruno stayed in a children's home called Sonnhalde. This was not an orphanage; it existed to give children a holiday in clean mountain air, and Bruno was probably sent to it for health reasons. Comments on Bruno's papers suggest that he was meant to stay for two months. In fact, according to the papers, he was registered there until 13 October in the same year, when he was placed with the Dossekkers.

Did any member of his family visit him during those months? It seems that they did.

In the late summer of 1998, after Wilkomirski discovered from Ganzfried that he had an "uncle", he decided to visit Max Grosjean in his home near Zurich. Grosjean showed Wilkomirski and Verena pictures of his "mother" and Bruno as a baby. No one present thought they looked alike, and Wilkomirski said the photograph of Yvonne Grosjean did not in any way match his memory of his mother. Then Grosjean told Bruno/Binjamin a little of the family history. In 1940, his sister was involved in a car accident and while she was in hospital it was discovered that she was pregnant. She was unmarried, and stayed in hospital until the birth. The uncle wanted to adopt Bruno, and sent his fiancee - his present wife - to see him in Adelboden. She was shown Bruno but told that it was too late to adopt him - a "doctor's family" had already been accepted as foster parents. Neither Max Grosjean nor his fiancee had ever seen Bruno again.

Wilkomirski talked to me about all this with remarkable ease. For him, Bruno Grosjean is a completely separate person. But when I expressed an interest in contacting the "uncle" myself, Wilkomirski said that it would not be a good idea to disturb him. Therefore I did.

On the telephone, Max Grosjean and his wife were quite happy to talk. They told me that Yvonne was very pretty but not very "reliable"; that she'd been hurt when a car had knocked her from her bicycle; that she didn't get along with her future sister-in-law, and so didn't want her brother to raise the child.

The first four years of Bruno's life are not at all clear. Before he reached Adelboden, he was in the legal care of the Biel authorities, but where was he - in an institution, with foster parents? Max Grosjean could not remember or would not say. But there are two photographs of mother and son together and the mother did, Mrs Grosjean said, visit him in the home in Adelboden at least once. When the adoption was agreed, she was not allowed to know where Bruno would go.

Then he used a word that I'd first heard from Wilkomirski. He said that he and his sister had been Verdingkinder. He said it sadly, and hinted at suffering. Verdingkinder (roughly, "earning children") were the children of the poor, sometimes orphans, sometimes illegitimate, sometimes with parents too impoverished to keep them. They formed a caste of children who provided labour for peasant families, in exchange for shelter and food. In the last century, Verdingkinder were sometimes sold at auction; they were often beaten and sexually abused. The system was abolished in the 1950s, but not before it had separated Bruno's mother and uncle when they were children; and, perhaps, made Bruno, as the illegitimate child of a Verdingkind, a candidate for separation from his mother, with or without her consent.

I am not a psychologist; the temptations and dangers of literary or any other kind of psychology for the amateur are well known. Still, the similarities between Fragments, the early life of Binjamin Wilkomirski, and what we know of the early life of the real Bruno Grosjean are too striking to resist: obscure origins in a social class that polite Swiss society would rather not discuss; a childhood swamped with loss and change; institutions which might easily seem like child-prisons; distant memories of motherhood. In the book, the mother-substitute Frau Grosz. In life, his mother, Frau Grosjean. "I looked at her," writes Wilkomirski of Frau Grosz as they travel on the train from Poland to Basle. "She was staring at her hands and seemed to be a long way away. Something important, something that couldn't be changed, was going to happen." Whether this is Grosz or Grosjean, Binjamin or Bruno, the destination is the same: adoption, the Dossekkers, a certain luxury but also coldness and formality in that villa in Zurich, in a country where Binjamin/Bruno will begin to feel separate, and which he will come to dislike.

To remove himself as far as possible from his native environment, he declared himself a Jew. If he sought a sense of community in Judaism, I doubt that he has found it - he practises a very solitary form. But to Bruno Dossekker, being a Jew was synonymous with the Holocaust. Swiss history has nothing remotely similar to offer, nothing so dramatic to survive, or to explain to a man where he came from, or how he is.

Elena Lappin. This is an abridged version of 'The Man with Two Heads', which appears in 'Granta' magazine's 'Truth and Lies' issue, available in bookshops for pounds 8.99 or direct from 'Granta' for pounds 6.99, or free with a year's subscription to 'Granta' (four issues for just pounds 21.95 to Independent on Sunday readers). Phone or fax 'Granta' on 0500 004 033