KYIV, Ukraine (AP) — A 21-year-old Russian soldier facing the first war crimes trial since Moscow invaded Ukraine pleaded guilty Wednesday to killing an unarmed civilian.

Seargeant Vadim Shishimarin could get life in prison for allegedly shooting a a 62-year-old Ukrainian man in the head through an open car window in the northeastern Sumy region on February 28, four days into the invasion.

Shishimarin, a captured member of a Russian tank unit, was prosecuted under a section of the Ukrainian criminal code that addresses the laws and customs of war.

“The … accused Shishimarin fully admitted the guilt of the crime in accordance with all circumstances established during the pre-trial investigation and announced by the prosecution during the trial today,” prosecutor Yaroslav Uschapivskyi said.

“(Shishimarin) was instructed (to shoot a civilian) by a person who wasn’t his direct commander or a person whose instructions he was obliged to follow,” Uschapivskyi added. “So it’s not correct to say that there was some sort of order.”

Ukrainian Prosecutor General Iryna Venediktova previously said her office was readying war crimes cases against 41 Russian soldiers for offenses that included bombing civilian infrastructure, killing civilians, rape and looting.

It was not immediately clear how many of the suspects are in Ukrainian hands and how many would be tried in absentia.

Prosecutors plan to continue presenting evidence against Shishimarin following his guilty plea.

As the inaugural war-crimes case in Ukraine, Shishimarin’s prosecution was being watched closely. Investigators have been collecting evidence of possible war crimes to bring before the International Criminal Court in The Hague.

Victor Ovsyanikov, Shishimarin’s attorney, said Wednesday that despite the guilty plea he believed the soldier’s actions were “wrongly qualified.”