The witnesses told the court that an investigation into the murder of Vinko Cicak and his sons Ivan, Ante and Mate established that they were shot dead at close range but that it could not be established who killed them.
There were no traces of any fighting at the murder site, according to their testimony.
"At the site of the murder we found the four bodies. There were no physicians to perform an autopsy. Wounds were visible on the corpses and I concluded that they were close-range gunshot wounds," Stojic told the court today adding that he had found bullet cases some 10 metres from the bodies.
Kojic, who together with Stojic was present at the on-site investigation, testified about the destroyed farm where the bodies were found.
Kojic said he could not say anything else about that as he was not directly involved in the on-site investigation.
The trial opened on 1 November 2010, with first defendant Zoran Vuksic and second defendant Slobodan Strigic pleading not guilty. Third defendant Branko Hrnjak pleaded guilty, while the fourth accused Velimir Bertic pleaded not guilty.
The defendants are charged with the murder of at least six non-Serb civilians, unlawful detention, physical abuse, intimidation, terror, torture and inhumane treatment.
According to the indictment, husband and wife Adam and Ana Baric were killed on 10 October 1991, while Vinko Cicak and his sons Ivan, Ante and Mate were killed on 17 October.
Zoran Madzarac is also suspected of involvement in this case, but he is on the run.
On 6 December prosecution witness Jadranka Cicak identified the first defendant Zoran Vuksic as one of the persons involved in the killing of four members of her family.
Cicak said that on 17 October, 1991, Vuksic and Zoran Madzarac, both wearing camouflage uniforms, came to her place in the company of two other men in police uniforms, accusing her family of stealing pigs and telling them to come to the police station to make a statement.
The witness said that her husband, Ivan Cicak, his brothers Ante and Mate, and their father Vinko, went to the police station and that it was the last time she saw them.
The case was referred to the Serbian State Prosecutor's Office by the Osijek County Prosecutor's Office in Croatia in 2008, based on the agreement between the two countries on cooperation in the prosecution of war crimes, crimes against humanity and genocide.
The trial will resume in February.