At the start of the trial at the Belgrade War Crimes Tribunal on Monday, the first defendant Zoran Vuksic entered a plea of not guilty, and the second defendant Slobodan Strigic also denied involvement in the killings alleged in the indictment.
The Serbian citizens Vuksic, Strigic, Hrnjak and Bertic, who used to be members of a unit for special purposes of Serb paramilitary forces of the so-called Serb Autonomous Region of Slavonia, Baranja and Western Srijem, are charged with killing at least six non-Serb civilians.
Under the indictment, the victims are Adam Baric and his wife Ana, killed on 10 October 1991, and Vinko Cicak and his sons Ivan, Ante and Mate, killed on 17 October 1991.
The defendants are also charged with illegal detention, intimidation, torture and inhumane treatment.
Presenting his defence, Hrnjak today said that on 17 October 1991 he was on duty in the local police station when Vuksic and Zoran Madzarac arrived and told him that he should "transport four Croatian spies in a Black Maria".
As they were driving, Hrnjak said, at one moment he was told to pull over, after which the four members of the Cicak family were taken out of the vehicle one by one and killed.
Vuksic stabbed the first man to death, and shot the second and the third victim to their heads. Strigic opened fire at the remaining member of the Cicak family as he was being pulled out of the van, but the defendant Hrnjak did not know whether it was Strigic who killed him.
Hrnjak said that later on the same day Vuksic threatened him to keep silent about the murders or somebody from his family would be killed. During an encounter in 2009, Strigic told Hrnjak not to mention him in the event of his arrest.
"Don't mention my name. You have children and I have brothers," Hrnjak quoted Strigic as telling him in 2009.
Strigic today countered by saying that Hrnjak was not telling the truth.
Strigic said he had not threatened Hrnjak and added that it was him who had reported the crime in 1997, which was why he had had no reason to hide.
Croatian authorities referred the case to Serbian war crimes prosecutors in 2008 in line with an agreement on the prosecution of war crimes, crimes against humanity and genocide, signed between the two countries in 2006.