- Vadim Shishimarin is accused of killing a 62-year-old man in northeast Ukraine on 28 February.
- Shishimarin, 21, has been charged with war crimes and premeditated murder.
- He faces a possible life sentence.
A Russian soldier pleaded guilty on Wednesday to killing a Ukrainian civilian in the opening stages of Moscow's invasion during the first war-crimes trial held since the war began.
The hearing in a packed Kyiv courtroom is the first in a series of proceedings being brought by Ukraine against Russian servicemen who have been accused of carrying out atrocities by Kyiv and its Western allies.
They are also a public test of Ukraine's judicial system at a time when international institutions are simultaneously investigating abuses allegedly committed by Russian forces.
Russian soldier Vadim Shishimarin is accused of killing a 62-year-old man in northeast Ukraine on 28 February, just four days into the Russian invasion.
The 21-year-old from the Siberian region of Irkutsk in eastern Russia has been charged with war crimes and premeditated murder faces a possible life sentence.
Asked in court if he was guilty of killing the elderly civilian, the sergeant responded "yes".
The Kremlin said earlier Wednesday that it had "no information about the case".
Moscow's "ability to provide assistance due to the lack of our diplomatic mission there is also very limited," Kremlin spokesman Dmitry Peskov told reporters.
Wearing a blue and grey hoodie, the youthful-looking soldier with a shaved head looked towards the ground as a prosecutor read out charges against him in Ukrainian.
Viktor Ovsyannikov, the soldier's lawyer, said he would build his case after hearing "testimonies of witnesses" and described the trial as without precedent.
"In Ukraine, this is the first criminal case of this type. Judges have never before announced these kinds of verdicts," he said following the hearing.
"If we're talking about murder, then in our legislation there are several articles that punish this kind of action."
- 'Sending a clear signal -
He added that he had not liaised with anyone in Russia on the case, with the exception of Shishimarin's mother.
"No Russian officials have consulted with me. I have provided her with all the necessary explanations," he said.
Ukrainian authorities had earlier said the Russian soldier was cooperating with investigators.
Prosecutor Andriy Sinyuk told reporters that two witnesses - including one of the Russian soldiers who was with Shishimarin at the time of the incident - will be brought to testify in court.
The soldier's weapon will also be examined as part of the probe, he said.
Prosecutors say Shishimarin was commanding a unit in a tank division when his convoy came under attack.
He and four other soldiers stole a car, and as they travelled near the village of Chupakhivka in the Sumy region, they encountered a 62-year-old man on a bicycle.
The prosecutor's office said:
Shishimarin then fired a Kalashnikov assault rifle from the window of the vehicle and "the man died instantly, a few dozen metres from his home", they added in a statement.
Ukraine authorities announced the soldier's arrest earlier in May alongside a video in which Shishimarin said he was fighting to "support his mother financially".
Ukraine's chief prosecutor Iryna Venediktova on Twitter said there were "over 11 000 ongoing cases of war crimes and already 40 suspects".
"By this first trial, we are sending a clear signal that every perpetrator, every person who ordered or assisted in the commission of crimes in Ukraine shall not avoid responsibility," she said.
Oleksandr Pavlichenko, the head of the Ukrainian Helsinki Group for Human Rights, said that in the Shishimarin case "the motivation is not only legal, but political as well."
What is at stake, he said, is whether Ukraine "will have a real judicial process or just a play for the public".
The trial is due to continue on Thursday, when two more Russian servicemen are expected in a central Ukraine court for firing rockets at civilian infrastructure in the northeastern Kharkiv region.
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