KYIV, Ukraine (AP) — A Russian soldier went on trial in Ukraine on Friday for the killing of an unarmed civilian, marking the first time a member of the Russian military has been prosecuted for a war crime during the 11-week conflict.

A 21-year-old captured member of a tank unit is accused of shooting a 62-year-old Ukrainian man in the head through an open car window in the northeastern village of Chupakhivka during the war’s first week.

Scores of journalists and cameras packed inside a small courtroom at the Solomyanskyy district court in Kyiv, where the suspect, Sgt. Vadim Shyshimarin, appeared in a small glass cage wearing a blue and grey outfit.

He faces up to life in prison under the penalties spelled out in the section of the Ukrainian criminal code that addresses the laws and customs of war. Ukraine’s top prosecutor is investigating allegations that Russian troops violated Ukrainian and international law by killing, torturing and abusing possibly thousands of Ukrainian civilians.

The judges and lawyers in Shyshimarin's case discussed procedural matters briefly before the judges left the courtroom and then returned to say the proceedings would continue on another day.

Defense attorney Victor Ovsyanikov acknowledged that the case against the soldier is strong but said the final decision over what evidence to allow will be made by the court in Kyiv. Ovsyanikov said Thursday that he and his client had not yet decided how he will plead.

As the inaugural war-crimes case in Ukraine, Shyshimarin’s prosecution is being watched closely.

Prosecutor General Iryna Venediktova's office has said it is looking into more than 10,700 potential war crimes involving more than 600 suspects, including Russian soldiers and government officials.

Many of the alleged atrocities came to light last month after Moscow’s forces ended their bid to capture Kyiv and withdrew from around the capital, exposing mass graves and streets and yards strewn with bodies in towns such as Bucha.

Volodymyr Yavorskyy, coordinator at the Center for Civil Liberties in Kyiv, one of Ukraine’s largest human rights groups, said activists will monitor the Russian soldier’s trial to ensure that his legal rights are protected. It can be difficult, he said, to maintain the neutrality of court proceedings during wartime.

The observance of the trial's rules and norms "will determine how similar cases will be handled in the future,” Yavorskyy said.

Vadim Karasev, an independent Kyiv-based political analyst, said it’s important for Ukrainian authorities "to demonstrate that the war crimes will be solved and those responsible will be brought to justice in line with international standards.”

Over the past week, Venediktova, her office and the Security Service of Ukraine, the country's law enforcement agency, have posted a few details from the investigation into Shyshimarin's actions on their social media accounts.

On Feb. 28, four days after Russia invaded Ukraine, Shyshimarin was among a group of Russian troops that had been defeated by Ukrainian forces, according to Venediktova's account. As the Russians fled, they fired at a private car and seized the vehicle. They then drove to Chupahivka, a village in the Sumy region about 200 miles east of Kyiv.

On the way, Venediktova said, the Russian soldiers saw a man walking on the sidewalk and talking on his phone. Shyshimarin was ordered to kill the man so he wouldn't be able to report them to Ukrainian military authorities. She does not identify who gave the order.

Shyshimarin fired his Kalashnikov rifle through the open window and hit the victim in the head.

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

The Security Service of Ukraine, known as the SBU, posted a short video on May 4 of Shyshimarin speaking in front of camera and briefly describing how he shot the man. The SBU described the video as “one of the first confessions of the enemy invaders."

“I was ordered to shoot,” said Shyshimarin, wearing a blue and gray hooded sweatshirt. “I shot one (round) at him. He falls. And we kept on going.”

Lardner reported from Washington.