A 21-year-old Russian soldier pleaded guilty Wednesday to killing an unarmed Ukrainian civilian in the first war crimes case Kyiv has brought since the Russian invasion three months ago.

Sergeant Vadim Shishimarin could be sentenced to life in prison for shooting a 62-year-old Ukrainian man in the head through an open car window four days after Russia launched the invasion in late February. 

Ukrainian Prosecutor General Iryna Venediktova previously has said her office is preparing war crimes cases against 41 Russian soldiers for offenses that included bombing civilian infrastructure, killing civilians, rape and looting. It is not clear how many of the Russians are in Ukrainian custody or how many might be tried in absentia.

In Shishimarin’s case heard in a Kyiv court, Venediktova alleged that he was among a group of Russian soldiers that fled Ukrainian forces on February 28, driving to Chupakhivka, a village about 320 kilometers east of the capital, Kyiv.

The prosecutor-general said that on the way the Russian soldiers saw a man riding his bicycle and talking on his phone. Shishimarin, according to Venediktova, was ordered to kill the man so he wouldn’t be able to report them to Ukrainian military authorities but did not say who gave the order.

Shishimarin fired his Kalashnikov rifle through the open window and hit the victim in the head, Venediktova wrote in a Facebook account.

“The man died on the spot just a few dozen meters from his house,” she said.

In a brief video account of the incident produced by the Ukrainian Security Service, Shishimarin said, “I was ordered to shoot. I shot one (round) at him. He falls. And we kept on going.” 

Venediktova’s office has said it is investigating more than 10,700 potential war crimes involving more than 600 suspects, including Russian soldiers and government officials. International authorities are also investigating possible Russian war crimes, while Moscow is believed to be working on crimes cases against Ukrainian troops.

Russia has denied targeting civilians and accused Ukraine of staging atrocities. Ukraine says thousands of its civilians have been killed.

Some material in this report came from The Associated Press.