Some of the Wagner Group's troops who have fought in Syria
A video has emerged purporting to show Russian mercenaries torturing and beheading a Syrian army deserter, in what is thought to be rare footage of Moscow's shadowy paramilitary outfit operating in Syria.
The video, which dates to 2017 but was only released in full on Russian social media site VK last week, appears to show Russian-speaking fighters striking the man with a sledgehammer before decapitating him and lynching his body.
It came to the attention of online sleuths who used open-source intelligence to geolocate the footage to al-Shaer oil fields in Homs, central Syria, which was under Russian and Syrian government control at the time of the attack.
Russia has been fighting on the side of Syrian President Bashar al-Assad since it intervened in the war in 2015.
The Syrian army, depleted by mass defections and casualties, had been struggling before Vladimir Putin, the Russian president, decided to support the regime with air cover and troops on the ground.
The video is understood to have been posted last week on a private VK account linked to Russian security contractors called Wagner Group.
The private security firm, which is largely made up of retired Russian soldiers, has waged secret wars on the Kremlin's behalf in Ukraine, Syria and the Central African Republic in recent years.
Moscow has never publicly acknowledged their presence in Syria, however their role came to public attention after US air strikes on a Wagner position last year left dozens of contractors dead.
The group is known to have strict rules governing communication and social media use. Wagner employees have their phones confiscated while on missions and are banned from posting about them once home, making leaks such as this one rare.
Conflict Intelligence Teams, a Russian investigative journalism organisation which analysed the footage, noted that the fighters in the video were not wearing Russian Armed Forces' uniforms and that their weapons - AK-74 assault rifles and an RPK-74 machine gun - appeared to be relatively old models not used by Russian troops.
The victim in the video was named as Muhammad "Hamadi" Abdullah al-Ismail, 32, from Deir Ezzor, eastern Syria. Ismail had reportedly fled for neighbouring Lebanon seeking refuge a number of years ago.
He returned last year to Syria, where shortly after he was arrested and forcibly conscripted into the army.
Russian forces have played a key role in consolidating the Syrian president's position CREDIT: AFP
He was accused of trying to flee his post by the contractors, who are seen in the video - which is too graphic for The Telegraph to publish - briefly questioning him before pushing him to the ground.
They then laugh as the rein down blows of a sledgehammer on his legs, arms and torso. He is then beaten and kicked unconscious before the Russian men behead him and cut off his forearms.
Some are heard advising how best to do, while one is heard saying “this will happen to every Isis fighter" as they accuse him of being a jihadist simply for wanting to desert.
As the fighters begin lynching the body, they discuss where they should leave it: "Where the commander says," one of them says. “So, will we play football today?", asks another fighter as he kicks the decapitated head.
They hang him upside down by the feet and pose for a picture with his corpse before dousing it with petrol and lighting it on fire.
They discuss whether they should cover their faces for the video, but agree there is no point as "it’s not gonna go anywhere."
Russian forces and mercenaries have helped swing the war in Assad’s favour.
, he was a Syrian army deserter so they did this as a deterrent to all other soldiers who were thinking of bouncing cuz they were losing. 
