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.
A United Nations court has convicted six senior Bosnian Croats of atrocities against Muslims during the Bosnian war.
The war crimes trial of ex-Bosnian Serb commander General Ratko Mladic has been delayed by a judge in The Hague due to "errors" by prosecutors in disclosing evidence to defence lawyers.
Alphons Orie told the UN Yugoslav war crimes tribunal today he was delaying the case due to "significant disclosure errors" by prosecutors who are obliged to share all their evidence with Mladic's defence team.
He says judges are still analysing the "scope and full impact" of the error.
The second day of prosecution opening at the trial of former Bosnian Serb army chief Ratko Mladic will focus on the mass killings in Srebrenica in 1995.
The trial, which began on Wednesday, is being held at a war crimes court in The Hague.
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.
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.