One July day in 1995, a band of Bosnian Serb gunmen laid siege on Srebrenica, an eastern enclave populated by Muslims. On July 11, after days of shelling, their commander Ratklo Mladic entered the central town — part of a United Nations "safe haven," swollen with refugees from the Bosnian War — and delivered an ultimatum: that all Muslims in the area hand over their weapons.

Thousands of women and children were deported by bus, to Muslim territory. But around 1,000 men and boys, ages 12 to 77, were separated from the fold — and packed into a warehouse in nearby Kravica for "interrogation for suspected war crimes." By the next morning, all of them were dead. They were joined, over the course of a three-day campaign, by thousands more.

On Wednesday, Serbian police detained seven men who are accused of carrying out the bloodbath — the first ever arrests made by the country in connection to the Srebrenica killings.

Serbia's Chief War Crimes Prosecutor Vladimir Vukcevic told the Associated Press that authorities had carried out pre-dawn raids across Serbia, in pursuit of the suspects. All are former members of a special brigade of Bosnian Serb police. One suspect is still on the run.

Reuters reported that the seven men will likely face trial in Serbia, rather than in the Hague, where high-ranking Balkan leaders such as the former Serbian president Slobodan Milosevic were tried.

The Srebrenica Massacre — which ultimately saw more than 8,000 Bosnian Muslims killed by Bosnian Serb forces — is the only European atrocity to have been labeled a "genocide" by the United Nations since the Holocaust.

Witnesses to the warehouse slaughter said that Bosnian Serb forces pitched bombs through the windows and shot round upon round of automatic fire into the crowd. Still, the morning after the gunmen opened fire, 100 of the men and boys were alive. They were ordered to go outside — and promised that they would be spared. When they left the building, they were instead gunned down.

Other Srebrenica victims were brought to killing fields, where they were shot and piled into mass graves.

In recent decades, the Srebrenica Massacre has become the defining emblem of the 1992-95 Bosnian War — not only because of its savagery, but because of what came next: impunity for its perpetrators, and silence on the part of Serbia. Belgrade has been accused of some of the worst war crimes of the early 1990s, carried out as the socialist Yugoslavia broke apart.

Only in 2011 did Serb authorities hand over Mladic, the notorious warlord who orchestrated the Srebrenica slaughter, to the International Criminal Tribunal for the former Yugoslavia (ICTY) in the Hague.

"We are coming up on the 20th anniversary of these crimes in July," Lara Nettelfield, a lecturer at London's Royal Holloway University, told VICE News. "For surviving family members… the atmosphere of impunity makes the genocide ever more present in their daily lives."

One of the men arrested in Wednesday's sweep was Nedeljko Milidragovic, 58 — "Nedjo the Butcher" — who allegedly led the pursuit of Bosnian Muslims through Srebrenica. After the war, he moved to Belgrade where he married, had children, and started a trucking business.

Prosecutors allege that the start-up capital Milidragovic used to build the business was pillaged from his victims.

On Wednesday, Vekaric, the war crimes prosecutor, described the arrests as a moment of redemption — and a turning point in Serbia's post-war history. "We have never dealt with a crime of such proportions," Vekaric said. "It is very important for Serbia to take a clear position toward Srebrenica through a court process."

Post-conflict justice in the Balkans has been stymied by the fact that many wartime perpetrators are still held up as nationalist heroes by their respective communities. Many Serbs still revere figures like Mladic.

A 2011 poll by the Serbian government's Council for Cooperation with the Hague Tribunal found that some 40 percent of Serbian nationals consider Mladic a hero.

Authorities in Belgrade are thought to be facilitating the prosecution of Serbs because they are eager to curry favor with Brussels, with an eye to obtaining European Union membership. Significant is the fact that Bosnian and Serbian prosecutors collaborated in the lead-up to Wednesday's arrests.

The arrests follows an earlier raid, in December, by Bosnian and Serbia police; then, 15 people were apprehended in connection with a 1993 atrocity, in which 20 people were dragged of a train in Strpci and executed.

The Bosnian war killed around 100,000 and left millions displaced. The large majority of casualties were Bosnian Muslims.

The effort to find culpability for Srebrenica has, in recent years, extended beyond the Balkans. In July, a Dutch court ruled that its government was responsible for the deaths of 300 people during the Srebrenica Massacre — since a United Nations team of Dutch peacekeepers, stationed in the municipality, had failed to thwart the assault.

Indeed, when Bosnian Serb forces entered Srebrenica in July 1995, they met no resistance from the hundreds of lightly armed peacekeepers. Dutch forces eventually handed over, to Bosnian Serb Commander Mladic, 300 men and boys who had sought shelter at a UN compound — for "interrogation."

On July 16, a District Court in the Hague ruled that the peacekeepers should have anticipated what would happen to those men and boys, in Serb hands — and thus, that the Netherlands is liable for compensation. The lawsuit was brought on behalf of relatives of the victims, and followed decades of campaigning for trial.

The ruling was considered a landmark, since it held the Netherlands responsible for failures committed under UN auspices. And it remains contentious. Some critics claim that it will discourage countries from participating in international peacekeeping operations. Opponents say that the Dutch peacekeepers should have been found responsible for more of the Srebrenica deaths.

In January, Vukcevic told AP that former war criminals and nationalists in Serbia have pushed against Belgrade's recent effort to reinvestigate old wartime cases. Serb prosecutors and their families have reportedly received death threats — and accusations that they are working as American spies.

"We have stirred up a hornet's nest," the prosecutor said.