Hasan Nuhanovic has the eyes of a man who has seen too much. His day job is helping to pursue international sex traffickers. In the evenings and at weekends, he hunts for the remains of his murdered family. "There is no closure, closure only comes when we die," he says. "But I need to bury them."
Hasan's father Ibro, mother Nasiha and 18-year-old brother Muhamed were all killed in the Srebrenica massacre, Europe's largest act of genocide since the second world war. It is at the heart of the prosecution case against the former Bosnian Serb leader Radovan Karadzic, whose trial in the Hague is due to start next week.
On 11 July 1995, Karadzic's general, Ratko Mladic, launched an attack on the UN safe haven of Srebrenica, which was being guarded by a Dutch garrison. Hasan's family were among at least 6,000 men, women and children who sought refuge in the Dutch military base. Two days later the Dutch, terrified for their own lives, handed the refugees over to the Serbs. Hasan only survived because Mladic needed a skilled interpreter to translate his orders to the Dutch UN commander, Colonel Tom Karremans.
When I spoke to him earlier this year, Hasan told me of a grim development. "Next week I am going to my hometown, Vlasenica, to meet one of the local Serbs who says he'll show me where my mother is buried. He is jobless and says he wants money, maybe £1,000, and then he will tell me where she is."
"So what are you going to do?" I asked. Hasan paused, obviously undecided. "I think I am going to offer to pay half, and to pay the rest if DNA analysis shows that it really is her."
When I first got to know Hasan in 2001, while researching a piece, he had already been searching for his family for six years. He agreed, over gritty black coffee in a roadside bar, to take me to the Dutch base at Srebrenica, and to tell me what happened there in July 1995.
Two days later, we met outside a disused battery factory in the small village of Potocari, just down the road from Srebrenica. Its vast, empty production hall echoed to the sound of a lumber business's rotary saws which tucked into some smaller, warmer room off to the side.
"This space was full," Hasan told me, gesturing to the bullet-riddled walls. "There were 6,000 people. They were told to sit down by the Dutch soldiers. They were not allowed to go to the toilet, so they did everything here. The temperature was 35C. The place stank so much it was almost impossible to breathe."
Outside, the Serbs waited for the Dutch to cave in. Then Hasan was told to climb on to an army truck and address the crowd. "They handed me a megaphone and said, 'Shout to the people to start leaving the base,' but the Dutch would not tell them what was waiting outside."
In an echo of the Holocaust, people were told to hand over possessions on the way out of the factory hall. "There were Dutch soldiers either side, fully armed, with machine guns. They told the people: 'Empty your wallets, empty your bags, empty your purses.'"
We climbed the cracked concrete stairs to the deserted factory's offices, which served as the Dutch soldiers' quarters. This is where Hasan had worked for the Dutch commander Karremans, at the heart of events, but powerless to influence them.
"My name was on a list of people who could stay in the base. My parents asked me to do everything I could to save my brother, and for two days I was trying to get his name on the list. They put his name on, maybe just to get rid of me, then erased it at the last moment. I was walking alongside him as he walked out of the base, trying to apologise and saying: 'I am coming with you!' He suddenly turned around and screamed at me: 'You are not coming with me! You will stay here!'"
I asked Hasan if he knew they were on their way to die. He turned to me, on edge. "Listen, the day before, Serb soldiers had shot at least nine men and boys lined up against the wall of that white house outside the base. They were shot in the backs of their heads. The Dutch soldiers saw it, it's written in their report."
Even now, it remains a mystery why the massacre was allowed to take place. The Dutch soldiers who failed to protect the people of Srebrenica were not alone. An SAS unit was in the town, radioing back a clear description of what was happening to Nato commanders, the most senior of whom was British general Michael Rose.
One of those SAS soldiers, a sergeant using the pseudonym Nick Cameron, wrote a book in which he describes telling his commanders about the impending massacre.
"I had visions of swarms of angry aircraft diving and destroying the attacking Serb targets at will," Cameron wrote. "There was nothing . . . we waited and waited." He said that his SAS commander later told him: "We never intended to fight for this place. That was never the plan." Cameron concluded "the whole UN thing was to get Srebrenica finished with."
Despite the fact that he had been awarded the Military Cross for bravery, the MoD took legal action against Cameron, and the book was withdrawn. He has not spoken about it since, and has not responded to my emails.
As we were leaving the factory, Hasan stopped and gestured at the field opposite, his breath condensing in the freezing air. "I have a vision in my mind for a memorial here. I see a sunny day; 10,000 headstones shining so strongly in the light that you can't even look at them. This is what I want to see. Not corn, not this dirty grass."
A few days after our visit, I met Hasan again outside a modern office building in the town of Tuzla, a couple of hours away. It was the headquarters of the International Commission on Missing Persons (ICMP), an organisation set up by Bill Clinton and funded by, among others, the British government to help relatives locate victims' remains. Hasan reported to the reception desk and was whisked into a clean, white cubicle. I watched as an ICMP worker quickly and expertly took a blood sample.
"It will be DNA-tested and entered on to our database," explained Adnan Rizvic, the head of the office. "Then it will be matched against samples taken from bodies we have exhumed from mass graves. Hopefully we will find a match.'
In order to understand ICMP's work, I asked to be allowed to visit its identification facilities. I was sent to a disused railway station in the small town of Lukavac on the outskirts of Tuzla. What I found there was a glimpse of hell.
One of the greatest obstacles to identification is "co-mingling". Most of the victims of the massacre were split up into smaller groups, executed and buried in mass graves. These graves were then re-opened over the next few months, using mechanical diggers to smash up and mix the bodies together, before moving them to "secondary graves" in a deliberate effort to hide them from war-crimes investigators.
Years later, in the basement of the railway station, investigators would strip what was left of the bodies, then jet-wash them until all that was left was bone, thousands of pieces. The clothes were sent to Tuzla to be laundered, photographed and catalogued by war crimes investigators.
Upstairs, to the deafening sound of dance music, a room full of anthropologists sorted through tablefuls of bones, quickly and expertly reassembling them into single skeletons. Sometimes there was an arm or leg missing; sometimes an arm or leg was all that was left. When they had finished, the air was torn by the scream of a hand-held saw. A small section of bone was cut from the skeleton, labelled, and sent to Sarajevo to be DNA-tested and matched against the blood samples given by surviving relatives.
After giving his sample, Hasan waited and waited, but there was no news. So he set about tracking down people who could tell him what happened to his family. It was dangerous work, as the only people who could help him were the Serbs.
At last he met a man who claimed he had seen his murdered mother's body. Hasan was told that instead of going with the other women, who were mostly spared, Naisha had tried to walk home, was captured, imprisoned and then murdered. "I asked him, how did she die? Tell me, was it with a gun or a knife? But he would not tell me, so I think it must have been with a knife."
Then, a couple of years ago, Hasan got a call from the ICMP to say that they had found remains of his father, Ibro. "They did not show me the remains, that is a good thing. They showed me a chart, and on it was marked the bones that were missing. They managed to put together more than 50% of his remains. Part of his skull was gone. I do not know if that was the cause of death, or something that happened when the Serbs dug up his body and re-buried it."
Every year, to mark the date of the massacre, there is a burial of all bodies identified and repatriated with their families over the previous year. Ibro Nuhanovic's funeral took place in the cemetery opposite the Dutch base at Potocari on 11 July 2007.
"There were three places in the cemetery reserved for members of my family," Hasan told me. "What I said to myself was that was one of the three. Now I need to find the other two."
I visited the cemetery in the autumn of 2007. The headstones turned out to be wooden, rather than the shining white marble that Hasan had envisaged. There were hundreds of them, row upon row of graves carefully tended by family members. The cemetery grows every year, as thousands more victims are identified by the ICMP.
A group of Muslim men, spotting my camera, came over and asked to shake my hand. They wanted to thank me for reporting the story. The reaction is a common one in Bosnia. Hasan told me, "I often feel that we have been forgotten."
Finally, a few months ago, Hasan got the news that, for £1,000, a man would tell him where his mother was buried. They met in secret near his home town of Vlasenica.
"He told me the name of the man who killed my mother. He said the bastard who killed her took the 1,500 deutschmarks she had on her. The next day she was killed alongside eight men. Shot in the head. He told me the bastard poured petrol over the bodies and burned them."
The man gave Hasan the location of his mother's grave. It turned out it had already been exhumed, and is in the backlog of cases waiting to be tested by the ICMP. "I rang them up and they confirmed that the bodies in the grave had been burned. They are going to do a DNA test on them."
It has taken months for Karadzic's case to make its way to trial. Central to the former Bosnian Serb leader's defence is his claim that former ambassador Richard Holbrooke offered him immunity from prosecution, in return for surrendering power. It is an allegation Holbrooke vehemently denies, but Karadzic is still trying to call the governments of countries he alleges were party to the agreement to testify. It may mean that the start of the trial, already postponed, is delayed again at the last minute.
And while Karadzic's case drags on, his general, Mladic, is still at large. It is possible he may never face trial, nor most of the soldiers who carried out his orders. The problem for Hasan, and tens of thousands like him, is that they depend on the local authorities to bring these men further down the chain of command to justice. He is not hopeful.
"It's good that Karadzic is on trial in the Hague, but what about the others? The ones who killed my family," he asks. "I see killers in the street every day, and so do the others who lost family members. There just aren't the resources to prosecute them all. I worry that the man who shot my mother will get away with it."
Hasan says that once he has found and buried all his family members, he will dedicate the rest of his life to pursuing justice for them.
"If you give me the choice between burying my family and achieving justice in the courts, I would take justice every time. There can be no reconciliation without justice."
This article first appeared in the Guardian on 12th October 2009.