THE HAGUE, Netherlands -- The Bosnian Serb commander of the forces that killed, raped and pillaged the homes of Bosnian Muslims during the 1992-1995 war stared impassively Monday as he listened to the story of one family’s tragedy.

For former Gen. Ratko Mladic, a man who’d once stood up to world powers as his forces rampaged through multi-ethnic Bosnia, it was a reminder of the human cost wrought by his drive to create an ethnically pure Serbian entity.

Mladic evaded arrest until May 2011. His trial – on charges of genocide, crimes against humanity and war crimes before a U.N. tribunal for the former Yugoslavia – began two months ago, but the first testimony was delayed until Monday because the prosecution, blaming a clerical error, had failed to share all its documents with his defense.

It was a tale of neighbors from the next village betraying their friendship, of an army in dissolution shelling defenseless citizens, and of families having to flee from village to village for months until captured in an ambush.

That’s when the army under Mladic’s command began to select civilians for execution – expelling women and children from their homes at gunpoint and disappearing and apparently killing their fathers, husbands and uncles.

Taking the stand as the trial’s opening witness, Elvedin Pasic described how in May 1992, his village of Hrvacani, not far from the north Bosnian town of Kotor Varos, got word by megaphone from the ethnically Serbian village next door. “Balijas,” it began, using a derogatory term for Bosnian Muslims. “Where’s the baklava? We’ll be there soon.”

Army tanks that had been stationed on both sides of Hrvacani shelled it through the night, said Pasic, who was 14 at the time.

By the next day, all but five elderly residents had fled the village. As they headed toward Plitska, a nearby village that was predominantly Roman Catholic Croat, Pasic and several dozen others came under fire.

“We had to crawl 100 or 200 meters through an open field,” said Pasic, who grew up in the United States and testified in English. “I was really terrified. Bullets were flying, picking up the ground.”

But the Bosnian Serb military kept them on the move. “It seems that everywhere we went, we were not welcomed,” Pasic said.

They went on to five villages, sometimes staying weeks, sometimes days. When the authorities found out they had taken refuge in Crkino Brdo, a Muslim village that had signed a loyalty agreement with the Serbs, they had to leave. The Croat village of Bilice gave them a warm welcome, but after several weeks they fled after learning that the village was about to fall.

Pasic, now 34, came close to losing his composure several times as he recounted the months of flight from village to village. Mladic, who’s now 70 and a lot thinner than in his days of absolute power, stared ahead without showing any emotion, occasionally sitting back in his chair, removing his eyeglasses or rifling through papers he had brought along in a large plastic attache case.

For the tribunal, established by the United Nations in 1993 in the midst of the three-and-a-half-year war, the tale was familiar. In calling Pasic as its first witness, the prosecution apparently was laying the groundwork for a case that Mladic, as the leader of Bosnian Serb forces, bore responsibility for the forces’ actions.