Nearly 10 years after Serb troops massacred close to 7,000 Muslim prisoners around this mountain town, war crimes investigators have all but wound up their probe into the killings, but express doubts that all major suspects will be brought to justice before a U.N. tribunal's scheduled closure in 2008.

As forensic experts complete the examination of a newly discovered mass grave, the two main targets of the war crimes manhunt remain at large. Ratko Mladic, who commanded the military forces of the breakaway Bosnian Serb state during the 1992-95 war, and Radovan Karadzic, its political leader, have been wanted men for a decade.

Preparations are underway in the town of Potocari near here for a July 11 ceremony marking the 10th anniversary of the worst atrocity in Europe since World War II.

Serbian President Boris Tadic has announced that he will attend the event, to be held at a cemetery where 2,000 of the victims lie. Serbian Prime Minister Vojislav Kostunica recently issued a statement denouncing the "massive crime" of Srebrenica.

Serbia has surrendered close to a dozen other war crimes suspects to the U.N. court this year, and this month, a half-dozen people in the part of Bosnia dominated by ethnic Serbs were arrested for alleged involvement in the massacre.

Despite gestures like these, deep suspicions remain. The Serbian parliament has refused to issue a condemnation of the massacre. And some Bosnian Muslims have called for Tadic to stay away from the ceremonies, saying his presence would signal that Serbia considers Srebrenica part of its territory.

So far, the U.N. court in The Hague has convicted several Serb perpetrators, some of whom are appealing the verdicts. Former Yugoslav president Slobodan Milosevic is on trial, and several other suspects await hearings. Bosnian Muslims also committed atrocities, investigators say. Naser Oric, the Bosnian Muslim military commander for Srebrenica, is on trial for overseeing the killing and expulsion of Serb civilians in the years before the massacre.

But for now, the wait for the two big names continues. Carla del Ponte, the chief U.N. war crimes prosecutor, has said she will not attend the anniversary event unless Mladic and Karadzic are captured.

Fears that the tribunal might shut down before Mladic, Karadzic and other suspects come to trial prompted the court president, Theodor Meron, to call for an extension. "I can already predict that trials will have to run into 2009," he told the U.N. Security Council in a report this month.

Today, Srebrenica looks eerily the same as a decade ago. Gutted buildings dominate the winding main road. A pair of new mosques replace a couple that the Serbs razed. About 6,000 Serbs live in the town and nearby villages, along with 4,000 Muslims. Members of the two groups barely speak to each other, townspeople say.

The sum of information on Srebrenica points to a methodical killing campaign. The deaths took place not in a single orgy of destruction and bloodletting, but in a step-by-step process of capture, transfer, distribution and execution of thousands of detainees in multiple places around the town over four days, and by some accounts longer.

The killings took place two months before the end of the war. The United Nations had declared the town a "safe area" and stationed Dutch troops in it. But on July 11, 1995, Serb forces backed by tanks defied the United Nations and pushed straight into the town.

Hussein Karic, a Muslim who retired as a gamekeeper, returned from Sarajevo two years ago. He recalls being at his home above Srebrenica that day, when Serb forces started to descend from the mountains. He walked with a granddaughter to the town center, where hundreds of Muslims gathered. "I saw Mladic just a few feet away. He was trying to calm people. No one believed him," Karic said.

Karic joined a column of civilians heading for Potocari, down the valley. Occasionally, Muslim men were pulled out of the crowd and confined to buildings; there were screams and shots. "I kept circulating in the crowd. I didn't let anyone's eyes meet mine," Karic recalled.

Videos shot during the invasion showed Mladic moving about, patting little boys on the head and telling mothers not to wail. But at one point, he told Serbian television: "The time has come to take revenge on the Turks." Turks is the dismissive Serb label for Bosnian Muslims.

On July 13, buses arrived and a two-day evacuation began. Serb guards separated men from women and boys. Karic sneaked onto a bus for women and boys and stayed silent. He remembers looking into the eye of the driver. The driver did nothing. "I don't know why. It must be said some Serbs among the drivers knew there were men on board, but did not throw them off. It was God's will," Karic said.

Elsewhere, Serb guards were directing men and boys off the road, and women toward the trucks and buses. Sabaheta Fejzic recalls trying to shield her 16-year-old son. "The guards told me to go to the right, where the white buses were. 'Your son goes left.' . . . They grabbed him. I could not even cry, but my son was crying. I will never forget the tears falling from his eyes, his olive-colored eyes," she said, speaking slowly and pausing to recover from a sob.

"I knelt down and yelled out, 'Kill me.' One aimed a rifle at me. I said, 'Kill me.' But they said, 'Why waste the bullets?' And they threw me into a truck. It was all a haze after. I just see his olive eyes."

Captives were transported all over eastern Bosnia, war crimes investigators said: some just down the road to villages near the Drina River, others as far as 45 miles north, west as far as the outskirts of Sarajevo and several miles to the south.

Today, there are plenty of vivid traces of the operation. In the agricultural warehouse in Kravica, a few miles from Potocari, tribunal investigators say that scores of men and boys were packed into a long, white building and killed with bullets and grenades. Investigators have a photo of bodies piled up at the broad front doors.

Currently, the building is empty except for an occasional wandering goat. Bullet and shrapnel holes on the outside have been covered over. Inside, the walls are blackened by smoke and the bullets holes remain.

Similar remnants are visible in Pilica, 40 miles north, in a building called the Dom Kultura. Blackened flooring underneath a stage and pocked walls indicate shooting and fire within. There, on July 16, Serb soldiers killed prisoners, investigators say.

Drazen Erdemovic, a solder in the Serb army, confessed to shooting dozens of men in Pilica. In his defense, he said, "I had to do this. If I had refused, I would have been killed together with the victims. When I refused, they told me: 'If you are sorry for them, stand up, line up with them and we will kill you too.' " He was sentenced to five years in prison, his sentenced mitigated by his willingness to help investigators.

Investigators have identified numerous other places where prisoners were assembled and killed: a soccer field, a warehouse and a school in Bratunac, a warehouse in Konjevic Polje, a riverside at Drinjaca, a bend in the road at Nova Kasaba and a school and nearby dam at Petkovci. One of the worst mass executions occurred at a place called Branjevo farm, where more than 1,200 men and boys were shot down in a field.

Using aerial photographs, tribunal investigators have uncovered numerous grave sites filled with hundreds of bodies. Some of the bodies had been buried first at other sites, then dug up and moved in an attempt to hide evidence after the war ended. Many victims had their hands manacled or were blindfolded. In addition to the 2,000 corpses buried at the cemetery at Potocari, about 3,500 bodies remain in storage in Tuzla, Bosnia, where forensic experts are trying to identify them.

Last month, Serbian human rights campaigner Natasa Kandic, who has been investigating war crimes, provided a videotape of a unit of Serb soldiers called the Scorpions gunning down six Muslim men and boys at a house near Sarajevo. A vivid documentary account of an execution like this had never been found and shown before. It briefly set off a wave of soul-searching inside Serbia.

Nura Alispahic, a survivor of the killings, watched the tape at her home in Sarajevo. She later told reporters that her son Azmir was one of the prisoners: "I recognized his face, his shoes. That was my Azmir. They chased him, he turned around. I saw my enemies killing my child."

Azmir had left the family house in Srebrenica in an attempt to escape the town, but returned in a few minutes. "I forgot to kiss you, mother," Alispahic recalled him saying. That was the last time she saw him, or knew what happened to him, until the broadcast of the video in early June.

Investigators with the U.N. war crimes tribunal cleared soil and debris in 1996 from dozens of Srebrenica victims buried in a mass grave near Pilica.