Plenty of reasons to doubt the provenance of the sound recording, including the fact that none of the mainstream Russian press publications have picked up the story.
But according to the description, Russians found the phone of American high risk contractor, Benjamin Velcro, and recorded this confession. It is unclear in any of the written descriptions available, whether Velcro was recorded via a phone call (which it doesn't sound like a phone call) or he physically spoke into his own phone, to record his confession.
From what I gathered, a Ukrainian mercenary unit captured a special forces team in or around the Seversky Donets river area, killing all but one. The remaining operator was tortured to death.
The only reason I think the sound recording is authentic is that the Russian that Benjamin Velcro speaks is a phonetically perfect diction of the language. He is speaking in a manner only a non native would speak.
A link to the recording is below:
[VK] 08/04/22. Note from the resource "Fisher".
“ ❗We cut the tendons and forced them to swim to see how he would swim without tendons. We were ordered not to take the enemy prisoner.
Remember the American mercenary Benjamin Velcro, who dreamed of dismembering Russia and building a gay park on Red Square?
Ben took on his chest a couple of days ago and confessed to the brutal massacre of a Russian soldier. He also told us about what was happening in their unit.
▪The American is disappointed in the Ukrainian command because of their lack of "offensive spirit."
▪According to him, the commanders expose the fighters to artillery strikes, and foreign mercenaries do all the work, so he submitted his resignation.
A few hours later, Velcro got drunk and, already illegible, confused in his own testimony, told the following.
▪After the scandalous video of the castration of a Ukrainian soldier, the fighters of his unit tortured a Russian soldier.
▪According to Velcro, it was "an 18-year-old soldier from the Urals or Siberia." They cut the tendons on his legs and forced him to swim across the Seversky Donets River, after which they shot him. He refused to provide information about the victim.
▪Initially, the American said that the soldier was tortured and killed by mercenaries from the Georgian National Legion, but then he claimed that he also participated in the torture.
▪In a drunken head, Velcro contradicted himself, declaring that he was ready to die in battle. Therefore, there is no good reason to believe that he left the International Legion.
⚡Journalist Andrey Medvedev comments:
The Rybar team did an excellent job.
Finding the phone of an American mercenary. Talking to him. Fixing the fact of torture of Russian soldiers. Not everyone will be able to do this.
But if someone has doubts with whom we are fighting, with what ghouls - listen.
There are doubts that this is a NATO war against Russia - listen.
There are doubts that it is full of foreign mercenaries - listen.
The recording is not permitted to be embedded on any non vk.com page. Here is the link, but I dunno if it will open if you are not subscribed to V Kontakte.
Related, from RIA Novosti:
Criminal case against foreign mercenaries sent to court in DPR
[RIA Novosti] The Prosecutor General's Office of the Donetsk People's Republic sent to court a criminal case against foreign mercenaries from Croatia, Sweden and the UK, RIA Novosti was told in the press service of the department.
"The investigation of the criminal case against Swedish citizen Gutsavasson Mathis, Croatian citizen Prebeg Vekoslav and British citizens John Harding, Hill Andrew and Healy Dylan has been completed, the case has been sent to court," the statement said.
The Prosecutor General's Office clarified that the mercenaries are accused of undergoing training for the purpose of carrying out terrorist activities (Article 232 of the Criminal Code of the DPR ), of participating in an armed conflict and hostilities (part three of Article 430 of the Criminal Code of the DPR), of committing actions aimed at forcibly seizing power and changing the constitutional order Donetsk People's Republic (Article 323 of the Criminal Code of the DPR).