The Russian soldier, Vadim Shishimarin, 21, accused of war crimes in the first trial that opened in a Kiev court since the beginning of the invasion of Moscow, pleaded guilty.
Asked in court if he was guilty of the charges, including war crimes and premeditated murder, the sergeant replied "yes".
The first war crimes trial since the Russian invasion of Ukraine began today in Kiev.
The trial, which will be followed by many others, will be a kind of test for the Ukrainian judicial system at a time when international institutions are also conducting investigations into abuses committed by Russian military forces.
Vadim Shishimarin had appeared in court in Kiev on May 13 for the preliminary hearing.
He is accused of killing a 62-year-old man in northeastern Ukraine on February 28.
The young soldier from Irkutsk in Siberia, on whom charges of war crimes and premeditated murder hang, faces life imprisonment.
Ukrainian authorities said the young man is cooperating and admitting the events that took place just a few days after the Russian invasion.
According to investigators, Shishimarin was in charge of a Russian unit on a tank division when the convoy was attacked.
He and 4 other soldiers stole a car and, while traveling near the village of Shupakhivka, in the Sumy region, they allegedly met the 62-year-old on a bike.
"One of the soldiers ordered the accused to kill the civilian so he wouldn't report them," the prosecutor's office explained.
Shishimarin fired from a Kalashnikov from the window of the vehicle and "the man - the accusation adds - died instantly, a few tens of meters from his house".