During the Vukovar siege, the witness Radoje Trifunovic was in the JNA Guard Brigade and one of his duties was to write the war log.
Now a retired colonel of the Serbia and Montenegro Army, Trifunovic spoke in detail of the orders which Serb TO members in Vukovar and Seselj's volunteers received from the command of Operations Group South, namely Mrksic, Sljivancanin and Radic.
Trifunovic said that the commander, referring to Mrksic, had objective responsibility, in keeping with rules of conduct, for what was happening in his zone of responsibility even though he was absent for a short while.
Speaking of the treatment of prisoners of war, civilians and the wounded, Trifunovic mentioned "verbal abuse with attempted physical assault without serious consequences" in which the local population and the TO were involved.
Asked by the prosecutor if Mrksic was aware of that, Trifunovic said he did not know but that "as the commander he should have been informed of it".
The witness said he did not know either if Mrksic issued orders to his subordinates to protect prisoners.
Asked if from November 20 to 24, 1991, investigations were launched and disciplinary measures taken against soldiers who had abused prisoners, Trifunovic said he did not remember that any proceedings had been taken against anyone.
The prosecutor entered many JNA laws, regulations and handbooks as evidence.
Trifunovic said the JNA represented an integral whole and comprised the regular army and the TO. At times of war, the JNA could be augmented with volunteer units which enjoyed the same status as the regular army. He said that one commander was the superior of "all subjects in his zone of responsibility" and that all units in the Vukovar area were under the command of one commander, Colonel Mrksic.
In the autumn of 1991, Mrksic commanded the troops with the JNA Guard Brigade at the helm which were attacking Vukovar. He and his subordinate officers Sljivancanin and Radic were charged with crimes against humanity for the massacre of at least 264 Croatian wounded soldiers and civilians, abducted from Vukovar's general hospital and executed at nearby Ovcara farm on 20 November 1991.