A Wagner fighter defects to Norway, promising to expose Russian war crimes in Ukraine.

A former member of a notorious Russian paramilitary force has surrendered to Norwegian authorities, a rare defection that his lawyer and Russian human rights activists say could aid international probes into Moscow’s atrocities in Ukraine.

Andrei Medvedev, who says he commanded about 15 fighters in the Wagner mercenary group in Ukraine, has applied for asylum in Norway after being detained by local security forces for illegally crossing the nation’s border with Russia in the early hours of Friday, his lawyer, Brynjulf Risnes, said.

Norwegian immigration authorities confirmed that a man matching Mr. Medvedev’s description was detained and had requested asylum, but declined to comment further, citing security and privacy concerns.

In a video published on Monday, Mr. Medvedev told a Russian human rights activist, Vladimir Osechkin, that he had crossed into Norway on foot and requested asylum after surrendering to the police. He said he was willing to collaborate with international investigators into potential war crimes committed by Wagner, a major paramilitary force at the center of the Kremlin’s war efforts in Ukraine.

Mr. Risnes, the lawyer, said Mr. Medvedev’s case is the first of its kind in Norway, adding that it could set a precedent for how the West handles the defection of Russian fighters.

In a series of interviews with The New York Times before leaving Russia, Mr. Medvedev, 26, said he had joined Wagner in July and led a detachment made up primarily of enlisted prisoners in the battles around the eastern Ukrainian city of Bakhmut. The name of Mr. Medvedev’s unit was corroborated by one of his alleged subordinates, a recruited prisoner named Yevgeny Nuzhin, who was debriefed by Ukrainian forces after surrendering to them in September.

Mr. Nuzhin was returned to Wagner in a prison exchange soon after and executed for treason.

Mr. Medvedev said he deserted in November, before Mr. Nuzhin’s murder, and returned to Russia. There, he contacted Mr. Osechkin and other human rights activists for help. He moved between cities until his escape to Norway.

At one point, in November, he approached Wagner’s headquarters in St. Petersburg and handed his military dog tag to a security guard, a scene captured on video by his companion and uploaded on YouTube.

Mr. Medvedev’s own accounts of his life and military service have been contradictory at times, and he has declined to provide evidence for his most explosive claims.

Mr. Medvedev, who grew up in a Siberian orphanage and had served at least four years in jail for robbery, said he had witnessed on the front lines summary executions of Wagner fighters accused of cowardice and desertion, as well as dramatic casualty rates suffered by inmate units sent by commanders on suicide missions. The claims have not been independently verified.

Two acquaintances of Mr. Medvedev, who have met him since July, have confirmed that he had enlisted in Wagner, but were unable to confirm the details of his service. Their identities are being withheld to protect them against Wagner’s potential retaliation.

Mr. Medvedev’s contract with Wagner last year was the third time he had carried out military activities in Russian-occupied eastern Ukraine, according to people in Ukraine and Russia who met him at the time. He was previously in Donbas in 2015 and 2020, although his exact role and affiliation at the time is unclear.

Alina Lobzina contributed reporting.