As teams dig in the thick clay they hope to find answers for trials in The Hague and bring peace to families still searching for the dead.
Bosnia reburied another 409 victims of the Srebrenica massacre on the 18th anniversary of Europe's worst atrocity since the Holocaust.
The trial of Ratko Mladic, which the world has been waiting years for, has been adjourned indefinitely.
ITV News correspondent Paul Davies reported on the issue of Ratko Mladic's arrest warrant in 1996. Today the trial of the former Bosnian Serb general began at a war crimes court in The Hague. He faces 11 war crime charges, including two genocide counts. He denies all the charges.
Bosnian Serb general Ratko Mladic taunted Srebrenica survivors at the start of his trial for genocide, running his hand across his throat in a gesture of defiance to relatives of the worst massacre in Europe since World War Two.
Mladic, now 70, flashed a thumbs-up and clapped his hands as he entered the courtroom in The Hague, where he faces possible life imprisonment for allegedly leading the slaughter of 8,000 unarmed Muslim boys and men in Srebrenica in 1995.
Later, Mladic made eye contact with one of the Muslim women in the audience, running a hand across his throat, in a gesture that led Presiding judge Alphons Orie to hold a brief recess and order an end to "inappropriate interactions."
Munira Subasic, who lost 22 family members in the 1995 Srebrenica massacre, was among a group of relatives of the war dead standing outside the war crimes court in The Hague, as Mladic arrived for the start of his trial.
The 65-year-old said she wanted to look him in the eye "and ask him if he will repent for what he did".
Prosecutor Dermot Groome opened his statement by focusing on the plight of a 14-year-old boy whose father and uncle were among 150 men murdered by Bosnian Serb forces in November 1992.
He said Mladic's forces continued such killings through to 1995, when they massacred 8,000 Muslim men in the Srebrenica enclave.
"By the time Mladic and his troops murdered thousands in Srebrenica ... they were well-rehearsed in the craft of murder," Mr Groome told the court.
He showed judges video of the aftermath of a notorious shelling of a market in Markale, in the Bosnian capital Sarajevo, that killed dozens of people.
He said all the attacks were part of an "overarching" plan to ethnically cleanse parts of Bosnia of non-Serbs.
Prosecutors at a war crimes court in The Hague have begun to outline the charges faced by former Bosnian Serb army chief Ratko Mladic. The 70-year-old faces 11 war crime charges, including two genocide counts. He denies the charges.
Ratko Mladic is also held responsible for the siege and bombardment of the Bosnian capital Sarajevo, which killed 10,000 civilians. The prosecution described it as a plan to "spread terror among the civilian population".
In May 2011 he was arrested in a farmhouse in northern Serbia, penniless and in poor health. He recently had an operation for what is believed to have been a hernia, and during pre-trial hearings his attention appeared to wander.
Prosecutor Serge Brammertz has dismissed concerns that Mladic will find it difficult to sit through a 200-hour prosecution case involving testimony from 411 witnesses.
Prosecutors say Mladic was part of a "joint criminal enterprise to eliminate the Bosnian Muslims in Srebrenica by killing the men and boys ... and forcibly removing the women, young children and some elderly men".
They say Bosnian Serb forces (BSF) attempted to hide the slaughter by dumping victims in remote unmarked graves.
"When it became apparent that despite these efforts the world had learned of the mass murder of Srebrenica's Muslim men, BSF implemented (an) ... operation designed to further conceal the bodies and the crimes," said a pre-trial brief.
"Thousands of corpses were dug up with excavators, moved in trucks and dumped in even more remote locations."
Bodies were later found strewn across 17 primary and 37 secondary mass graves.
Former Bosnian Serb army chief Ratko Mladic was indicted in 1995 along with Radovan Karadzic, the Bosnian Serbs' political leader, although both remained free in former Yugoslavia for more than a decade before being arrested and passed to The Hague. Karadzic's trial is already under way.
Former Serbian president Slobodan Milosevic was indicted in 1999 and went on trial in The Hague in 2001, but died in 2006 before a verdict was reached.
Today the prosecution will present its case before Mladic and Judge Alphons Orie.
Mladic, one of the first big names from the wars - that followed the break-up of Yugoslavia - to be indicted by the court, is the last of them to go on trial.
The trial of former Bosnian Serb army chief Ratko Mladic begins at the Hague today, in a case that will establish if he was responsible for some of the worst atrocities in Europe since World War Two.
General Mladic, who is 70, faces 11 war crime charges, including two genocide counts. He denies the charges. General Mladic was arrested in Serbia last year after 16 years on the run.
He is charged with genocide at Srebrenica, where 7,500 Muslim men and boys were killed in July 1995. He also faces charges over the 43-month siege of Sarajevo, from May 1992 to November 1995.