The photographer Edward Serotta committed himself to documenting the story of the city. Then he committed himself anew - to helping a child. And the experience changed his life
As an American photographer based in Europe for the past eight years, going to Israel used to mean going to work. I stayed in a quiet, out-of-the-way hotel in Jerusalem's Arab quarter, took my meals in Yemini dives, and gossiped with other photographers about editors and reporters. Between jobs, I spent quiet hours in the collections of the Israel Museum.

These days, I stay at the Holiday Inn because it has a miniature golf course, tennis courts and a large swimming pool. I eat - exclusively - hamburgers and pizza. Conversations centre on basketball stars and racing cars. And to relax, I have found myself strapped into roller coasters, loping around on horseback and sitting in every horror movie playing in Tel Aviv.

Put it down to Denis Karalic, a 15-year-old boy I got to know in Sarajevo in November 1993 when I began work on a book about Bosnia's Jews during the current Balkan war.

As we got to know each other, it became clear that Denis had lived a life of rootlessness and uncertainty. His parents had all but abandoned him. I, alone and unmarried at 44, had no one to fuss over and care about. There was a hole in my heart. Denis found it and climbed in.

His mother, Magda, is a Polish Catholic. His father, Haris, a Bosnian Muslim. They met in the Seventies in Germany, where they were both working, and to celebrate their union they named their first son YugoPol.

Denis was born in 1980. Magda walked out on the family in 1988 to marry a Syrian while Denis and YugoPol were placed in an orphanage. Later that year, Haris, having found himself work in Bosnia, brought his sons to the small town of Donji Vakuf. YugoPol said he more or less abandoned them, and the older brother cared for the younger brother, feeding him, washing him, sending him to school.

The neighbourhood toughs beat them both up, calling them nazis, krauts. In 1990, they moved to Sarajevo, and, unable to get along with his father any longer, 15-year-old YugoPol could stand it no more and ran away to his mother in Germany. She shipped him off to her mother in Poland.

In Sarajevo, Denis and his father rented a room in the house of Nada Levy, who worked in the Jewish community centre. When war came and shelling closed the schools, Denis started following Nada to work. There he became one of the 54 volunteers who kept the non-sectarian Jewish humanitarian aid agency going. Supported by Britain's World Jewish Relief, Serbs, Muslims and Croats work together under the guidance of a handful of Holocaust survivors and their offspring. There, Denis felt at home. He became best friends with Nada's grandson Radoslav, who had been brought up by his mother Natalia to be a Serb. It was the boys' daily task to fetch water from the public spigot for the Jewish community's medical clinic and every morning, while the city went on dying, the Muslim and the Serb went off with their wagon, chatting non-stop, laughing and playing.

In January 1994, two mortar shells crashed into Nada Levy's house. Denis was blown across the room and peppered with glass in his hand and shoulder. It was a very lucky, if narrow, escape and it was enough for Radoslav's parents to volunteer to take both children out of Sarajevo to Israel. They had a meeting with Denis's father in the Jewish community centre, and I asked to sit in. Haris did not object, but he said he had nothing to contribute financially. Radoslav's parents looked at me helplessly. Their home and both cars had already gone up in flames. They were going to be on the dole wherever they went.

"This is your only stumbling block?" I asked Haris. He nodded, hang dog. I volunteered on the spot to support the boy outside Bosnia. I felt my face turning red. I started to ask myself, "For God's sake, what the hell are you getting into?" But the question answered itself: a life.

Denis himself was torn. Even if he wasn't much of a father, Haris Karalic was all that Denis had left in this world, and the boy could see clearly his father had no intention of leaving Sarajevo - not now, not ever. He could not bring himself to say he wanted to leave his dad behind; it was for the two of them to talk over, alone, although we all knew the outcome.

The World Jewish Relief convoy was scheduled to leave on 5 February 1994. The night before, Denis packed his clothes and some toys. When he had finished, he spent the night sobbing alone in his room. In the morning he began crying again, and held tightly on to his father's hand until he was gently nudged on to the bus. The tears flowed as he watched Haris slip away and the convoy rumbled out of the dying city. All the while I took pictures. I focused, I concentrated, I got the tears. And all the while I felt like a heel. "What are doing, Serotta," I asked myself, "buying yourself a story on the back of this boy's broken heart?" After all, photography feeds itself on the misery of others.

After we crossed the airport tarmac and slid through the front lines and into Bosnian Serb-held territory, after dark descended, Denis and I sat together. I told him about Israel: its weather, the beaches, the windsurfing. He said little and stared down at his shoes. By 2am, everyone else had drifted off to sleep; for the previous hour, Denis had been listening to my Walkman. Over and over he kept playing a Tom Petty song. Suddenly, he turned to me and said his first words. In German, he asked what he was listening to, and since it was English he needed a translation. I bent over and he let me hear the earphones. I smiled. "Fliegen lernen," I told him.

"Learning to fly." And even though he understood not a word, in the dark, in that rumbling bus, he sang along:

I started out on a dirty road

Started out all alone

And the sun went down as I crossed the hill

And the town lit up and the world got still

I'm learning to fly but I ain't got wings

Coming down is the hardest thing.

At about 4am, as we approached the border to Croat-held Herzegovina, he put on a brave face and started asking questions about Israel: the schools, the language, where the other children came from. Then, as he finally started yawning and his eyes fluttered a bit, he talked of how he wanted to get a job selling newspapers so he could send the money to his dad. As he fell asleep leaning against me, I could only imagine what was going on in the boy's heart. I resolved that night that, come what may, I would always be there for him. Someone had to be on his side.

Settling into Israel was not easy, even though Radoslav's parents were patient and loving. Denis knew he had a family out there in the world and he refused to believe they didn't want him. When I came to see him in Jerusalem, two months after he'd arrived, in April 1994, he said he wanted to get out of Israel as soon as possible. "But where would you go?" I asked. He turned red and yelled, "I was born in Germany! That's where I want to go and they have to take me!"

I didn't respond. A week later I went looking for his mother. Searching through the records of foreigners registered in Bavaria, I found her name in Augsburg. I caught a train down from Berlin and took a seedy hotel room. Then I gave a taxi driver the address. No one answered and I left a note on her door. Then I waited in the room, watched the rain fall, the cobblestones glisten and the lights go on. I wondered if I had gone completely crazy. At 11pm the phone finally rang. A very hesitant Magda Karalic agreed to meet me in a station cafe the following morning.

The last thing I wanted to do was sit before Magda Karalic like a social worker or judge. I tried to ask as few questions as possible. I couldn't help but ask why she had walked out on her children. She stared at me, then burst into tears. "Didn't you ever make a mistake?" I bit my tongue. Not like that, I wanted to say, but I remained silent.

Tears streamed down her face as she looked at pictures of her son. "So big... so beautiful..." she whispered. "So handsome." Of course she wanted to see her child again, she told me, but her husband would not allow Denis to live with them. "He's insanely jealous," she said. I took a $30 telephone card I had just purchased and slid it across the table to her, along with a telephone number for Denis. I could not imagine any mother needing more than that.

A week later she called me in a panic. Her husband had found my telephone number and was coming to Berlin to kill me. I laughed nervously. "What should I do, start lifting weights like in a Rocky movie?" He never showed up. Indeed, a few months later Magda said they had split up, but a reporter friend in Augsburg sent me a police report. The man had been murdered, shot in the head on a street in Warsaw. The report stated that "he was not unknown to the Augsburg police."

Since then, Magda Karalic has phoned Denis - but fewer than six times in 16 months. Then I sought out YugoPol, who drifts from Poland to Belgium and Germany, repairing cars, he said once, representing artists, he told me another time. He showed even less interest than his mother in being reunited with his brother.

As the weeks became months and the months stretched on, while his father didn't write, his mother didn't come and his brother didn't call, young Denis Karalic began settling into Israeli society. He studied harder in school and practised more on the basketball court than anyone else. Learning Hebrew was not a problem. After all, it was his third language, and soon he was speaking without even the trace of a foreign accent.

"He is determined to fit in," his teacher told me. "To be like everyone else here, and the other children really look up to him. You know, it's not hard for a teacher to spot a leader among followers, and in this capacity, Denis is something special. How can I put it?" she mused. "I guess I have to say it. There's an aura around him - more so because he refuses to have anything to do with anyone from ex-Yugoslavia. But," she hastened to add, "he comes to my house at night sometimes, and that's where his brave mask slips. I see him for what he really is, a little bird fallen from his nest. You know what he does when he comes to me and my family is gone and just the two of us are alone?"

I said I had no idea.

"He cries, that's all, he just cries."

When I visited Denis in June 1994, he said that perhaps, just perhaps, Israel wasn't so bad, that he might - might (he raised a finger of caution for emphasis) - want to stay and become a construction worker, just like his father. In January 1995, as we walked along a Tel Aviv street and stopped to watch a high-rise building going up, he announced, "I'm going to study architecture."

I told him that would take college.

He rolled his eyes the way all teenagers do when an adult says something infathomably stupid. "I know that."

"Gee," I said, continuing the dumb adult routine, "Who'll pay for all that?"

The boy threw his head back and laughed, then linked his arm in mine and we continued our walk