In the footage Yevgenny Nuzhin (55), shown with his head taped to a brick wall, said that he had changed sides on Sept 4
In an unverified video distributed on Telegram channels which Russian media said were linked to the Wagner mercenary group, the man identified himself as Yevgenny Nuzhin, 55, and said he had changed sides to "fight against the Russians".
In the footage, Nuzhin, shown with his head taped to a brick wall, gave his name, date of birth and said that he had changed sides on Sept. 4.
He said he was abducted in Kyiv on Oct. 11 and came around in a cellar.
"I got hit over the head and lost consciousness and came around in this cellar," he said. "They told me I was to be tried."
As he said those words, an unidentified man loitering in combat clothing behind Nuzhin, smashed a sledgehammer into the side of his head and neck.
Nuzhin collapsed onto the floor and the unidentified man delivered another blow to his head.
Reuters was unable to immediately verify the video, which the Grey Zone Telegram channel entitled "The hammer of revenge".
It was also unclear how Nuzhin, who told Ukrainian media in September that he wanted to fight for Ukraine, ended up in the hands of what appear to be Russian forces.
In a September interview, Nuzhin told Ukrainian media that he was a convicted killer who joined the Wagner group from jail but then changed sides and decided to fight against Russia and President Vladimir Putin.
Wagner group, originally staffed by veterans of the Russian armed forces, has fought in Libya, Syria, the Central African Republic, Mali and Ukraine, among other countries.
Wagner has been recruiting convicts in Russian jails in recent months, according to a video which showed Yevgeny Prigozhin, the founder of the Wagner mercenary group, speaking to convicts in a Russian jail. A senior U.S. defense official told reporters on Sept. 19 that the group was trying to recruit over 1,500 convicted felons to take part in Russia's war in Ukraine.
Asked to comment on the execution video, Prigozhin, the founder of the Wagner mercenary group, said in remarks released by his spokeswoman that the video should be called "A dog receives a dog's death."
Of Nuzhin, Prigozhin said: "He did not find happiness in Ukraine, and met with unkind but fair people."