Soldier killed one passenger, while the others pretended to be dead and survived.
The accused men are believed to still be stationed in the Zaporizhzhia region where the alleged abuses took place.
Although tanker was captured on the day his offence was committed, he was exchanged in a prisoner swap.
Case concerning the alleged abuse of civilians delayed after defence attorney said it fell outside his jurisdiction.
Defence lawyer contests circumstances surrounding identification of military man convicted of war crimes.
In March 2022, a drunk soldier hit and attempted to shoot a Ukrainian man after spotting a skull-shaped tattoo on his hand.
Victims suffered at least 12 gunshot wounds and died at the scene.
However, as a valuable exchange asset, Maksim Krishtop will not spend time in prison.
Hostages included people with severe chronic and mental illnesses.
Servicemen are accused of beating and starving 32-year-old hostage on several occasions.