OSLO -- Andrey Medvedev is tense. He arrives unsmiling. Sitting in a hotel lobby in central Oslo, he anxiously eyes a man walking past the bar, asking why he's looking at him.
Medvedev's anxiety is understandable. Until recently, he was a unit commander in the Wagner Group, the Russian private military company that has served as Kremlin shock troops in the war in Ukraine and is notorious for its brutal tactics.
A month ago, Medvedev fled Russia to Norway and started speaking out against Wagner, describing what he said were war crimes he said were committed by the group, including summary executions of those who refused to fight.
"I saw how they brought two people to the training ground and shot them publicly," Medvedev told ABC News this week.
He said the two Wagner troopers were executed to set an example for those who might refuse to go into battle, adding that such punishments were routine.
"The whole system is rooted in that," he said. "In the best outcome, they will badly beat someone up," Medvedev said. "In the worst outcome, they'll just shoot him."
Medvedev has applied for political asylum in Norway and is now living under the protection of the country's security agencies.
He gives a glimpse into the mercenary force that the Kremlin has increasingly come to lean on in its efforts to shift the war in its favor, according to Ukrainian officials and military experts. Founded by a close ally of President Vladimir Putin, for roughly a decade Wagner has operated overseas in conflicts, from Syria and to Libya, when the Russian government prefers to retain a veneer of deniability.
But since Russia invaded Ukraine, Wagner has swelled dramatically. It has acted as an army within an army, known for its pitiless methods, including sending waves of convicts into battle, according to Ukrainian troops on the ground. They have become particularly prominent in the battle for Bakhmut in eastern Ukraine, in January giving Russia its first notable battlefield advance in months when they seized the nearby town of Soledar.
Wagner has been allowed to recruit large numbers of convicts from Russia's prisons, promising to gain them pardons in exchange for fighting in Ukraine. Last year, a video emerged of Wagner's founder Yevgeny Prigozhin, personally addressing hundreds of inmates, offering them the chance to join and if they survived to go free. White House National Security Council spokesperson John Kirby told reporters the U.S. estimates Wagner has as many as 50,000 fighters in Ukraine. He said around 40,000 of them are convicts.
Medvedev said he saw many inmates while in Ukraine, sent into frontal attacks, with little training or equipment.
"They are throwing people in as meat, with small arms on armored vehicles," he said.
Medvedev, 26, said he joined Wagner last July. Originally from the Siberian city of Tomsk, he said he had first served in Russia's military as an 18-year-old conscript in Ukraine in 2014.
Because of that military experience, Medvedev said Wagner sent him to Ukraine two weeks after joining. But within days, he said he realized he had made a mistake, appalled at what he saw.
"I realized practically on the first day what was happening there. I understood what role Russia was playing on that territory," he said.
Before arriving, Medvedev said he had believed Kremlin propaganda that Russia was fighting a defensive war against fascists. But once there and speaking with local civilians, he said he realized he had been duped.
"Of course, in fact, I realized late," he said. "I didn't see anything like that, no fascists or Nazis. Ordinary people who were protecting their territory, their home."
After four months, he said he found a chance to escape. Going on the run, he said he spent two months hiding in Russia, moving between safe houses and being pursued by Wagner's security service. He was aided, he said, by a Russian human rights activist based in France who has helped other defectors.
In mid-January, Medvedev said, he finally crossed the border to Norway on foot by running across a frozen river.
He said he was now helping Norwegian police investigate a potential war crimes case against Wagner forces in Ukraine.
Medvedev said he believed Wagner might try to harm him in Norway. A videos posted online last year appeared to show Wagner contractors using a sledgehammer to execute a fighter they accused of surrendering. A video of a second apparent execution using a sledgehammer was posted by a Wagner-linked blogger on Monday.
But Medvedev said he wasn't afraid.
"I'm at risk. I'm not afraid," he said. "There's a Russian expression: if you're afraid of the wolves, don't go into the woods."
Wagner's founder, Prigozhin, has sought to leverage Wagner's role in Ukraine to grow his influence with Putin, according to Kremlin-watchers. Some observers believe he's even trying to position himself as a potential successor to Putin. In frequent social media posts, Prigozhin has presented Wagner as Russia's only capable fighting force, publicly slamming Russia's general staff.
Medvedev said he saw Prigozhin address Wagner troops in eastern Ukraine.
"'The Russian army has screwed up. We are the only ones fighting, that we're the only hope. The country puts its hope in us. That there are Germans there, fascists there, Nazis there,'" Medvedev recalled Prigozhin telling the men.
Western officials and some military analysts recently have suggested Wagner's costly tactics appear to have worn it down as a force, estimating thousands of its fighters have been killed and wounded in the fighting around Bakhmut. Recent reports in independent Russian media suggest the number of inmates willing to enlist has dried up as news of the slaughter has filtered back. This week, Prigozhin in an interview with a Russian blogger said Wagner was no longer recruiting prisoners.
Medvedev called a Wagner a "criminal organization." He said Russians had been deceived by their leaders and said he apologized to the Ukrainian people.
"It's not the Russian people who gathered on a square and took the decision to go to war against Ukraine. It was our authorities," he said.
"I believe that the people will end this war themselves. I really hope that all the same the people will take power in their hands and peace will really come," he said.