The first trial of a Russian soldier for war crimes in Ukraine since the invasion concluded Monday with Sgt. Vadim Shishimarin, a 21-year-old from Siberia, sentenced to life in prison for  premeditated murder and violating international laws for war.

Shishimarin, a captured Russian tank-unit sergeant, fatally shot Oleksandr Shelipov, a 62-year-old civilian, in the head in late February. Shishimarin had pleaded guilty, but his  defense had argued he was carrying out a direct order that he initially disobeyed.

“The guilt of the accused was fully confirmed,” the court ruled. “Shishimarin, being a Russian serviceman, violated the laws and customs of war.”

Last week Shishimarin had asked Shelipov’s widow, Kateryna, for forgiveness. She said she wanted a life sentence to be handed down, but also that she would be willing to see Shishimarin returned to Russia in an exchange for Ukrainian fighters who surrendered to Russian forces at the Azovstal steel plant in Mariupol.

During the trial the three-judge panel heard that Shishimarin was ordered to kill the man so he wouldn’t be able to report them to Ukrainian military authorities. Shishimarin fired his Kalashnikov rifle at the victim through the open window of a car.

“I was nervous about what was going on. I didn’t want to kill,” Shishimarin said at the hearing in Ukraine’s capital Kyiv. Judge Serhiy Ahafonov said he did not consider the defendant’s remorse sincere.

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. Venediktova’s office has collected more than 10,700 allegations of war crimes against Russia involving more than 600 suspects, including Russian soldiers and government officials.

Latest developments:

►The Russian military on Monday released footage of de-mining specialists working at the Azostal steel mill in Mariupol. Russia’s Defense Ministry told state-run RIA Novosti news agency that more than 100 explosives were destroyed since the final Ukraine holdouts surrendered.