Depraved militants fighting for the Islamic State in Iraq have savagely beheaded a man accused of practising sorcery and witchcraft. Harrowing images of the killing are being shared by bloodthirsty supporters of the terror group on social media and show the victim lying in a pool of blood with his severed head resting on his back. One of those distributing the sickening pictures is a man claiming to be a British militant fighting for the terror group who goes by the nom de guerre Abu Bakr al-Britani. The gruesome photographs are understood to have been taken near Tikrit in Iraq's Salah al-Din province, where members of the Iraqi Army and allied Shiite volunteer militias have had great success in forcing the terrorists to withdraw in recent weeks. Scroll down for video . Sick: This photograph shows the blindfolded and bound man wearing a brown jumpsuit as a bearded terrorist lifts an 18-inch long kukri machete high into the air ready to behead the defenceless victim . Harrowing: This image - far too gruesome to publish in full - shows a close-up of the man's lifeless body, with his severed head resting on his back and surrounded by prayer beads . The exact crime the beheading victim is accused of committing is not known, but images of his violent death were uploaded to Twitter saying he was a 'sorcerer'. Terror: One of those distributing the images is a man claiming to be a British ISIS jihadi who goes by the nom de guerre Abu Bakr al-Britani . The first photo shows the blindfolded and bound man wearing a brown jumpsuit as a bearded terrorist lifts an 18-inch long kukri machete high into the air ready to behead the defenceless victim. A second image far too gruesome to publish in full then shows a close-up of the man's lifeless body, with his severed head resting on his back. It is the exactly the same position British and American hostages are placed in after being savagely beheaded by ISIS' British executioner in chief Mohammed Emwazi, also known as Jihadi John. Surrounding the man's lifeless body are dozens of brightly-coloured prayer beads. It is likely the man had been selling the items, which ISIS terrorists consider bid’ah, meaning a 'reprehensible innovation'. As is so often the case with ISIS' brutal public executions and amputations, huge crowds are seen in the streets to witness the man's beheading. Young men and children and seen lining up in a town square and jostling for position as they struggle to get a better view of the atrocity. Horror: The execution in Salah al-Din took place as Iraqi forensic teams working in the nearby, newly liberated city of Tikrit started exhuming bodies from mass graves believed to contain the bodies of up to 1,700 soldiers . Girsly task: ISIS overran Saddam Hussein's hometown last June, capturing the 1,700 soldiers as they were trying to flee Camp Speicher - an air base previously used by U.S. troops on the outskirt of Tikrit . The execution in Salah al-Din province took place as Iraqi forensic teams working in the nearby, newly liberated city of Tikrit started exhuming bodies from mass graves believed to contain the bodies of up to 1,700 soldiers brutally murdered by ISIS last year. Kamil Amin from Iraq's Human Rights Ministry said the work started on Monday on eight locations inside Tikrit's complex of presidential palaces, where much of the killing took place. ISIS overran Saddam Hussein's hometown last June, capturing around 1,700 soldiers as they were trying to flee Camp Speicher, an air base previously used by U.S. troops on the outskirt of Tikrit. Later, the Islamic State group posted graphic images online that appeared to show its gunmen massacring scores of the soldiers after loading the captives onto flatbed trucks and then forcing them to lay face-down in a shallow ditch, their arms tied behind their backs. Militants fighting for the Islamic State in Syria and Iraq are being led by a highly secretive group of strategists and officials that were once senior figures in Saddam Hussein's army. Despite thousands of foreign fighters flocking to join the Sunni extremist group and starring in their propaganda videos, ISIS' leadership is dominated by ex-members of the late Iraqi dictator's military. Almost all of the regional commanders appointed by ISIS' leader and self-declared caliph, Abu Bakr al-Baghdadi, played prominent roles in the Baathist army before the 2003 invasion of Iraq and became involved with ISIS either in the resulting insurgency or after the dictator's 2006 death. Influence: Despite thousands of foreign fighters flocking to join the Sunni extremist group and starring in their propaganda videos, ISIS' leadership is dominated by ex-members of the military of Saddam Hussein . One former Syrian rebel who became an ISIS regional commander told the Washington Post that he found that almost all of the highly secretive officials overseeing all aspects to the terror group's day-to-day business were ex members of Hussein's Baathist army. During one meeting in which he dared to disagree with fellow commanders at an ISIS meeting, the man calling himself Abu Hamza was placed under arrest on the orders of a masked man who had sat silently and almost unnoticed at the side of the room, listening and taking notes. Although the enigmatic commander's real name was never revealed to him, Hamza said that he later discovered that the man had been an intelligence officer for the Iraqi army before joining ISIS. The same went for the other ISIS commanders Hamza met, who either used code names or no names at all in the hope of concealing their past as members of Hussein's army. As well as their extensive military expertise, another key element of the commanders' appointments has been the fact the ex-Baathists have extensive contacts among oil smugglers thanks to Hussein's efforts to avoid international sanctions in the 1990s. Crucially, oil smuggling is considered the most lucrative aspect of ISIS' £2 billion-a-year income.
Terrorists beheaded the man in a public square in Salah al-Din province .
Huge crowds gathered in the streets to watch the group's latest atrocity .
The victim is believed to have been killed after he was accused of sorcery .
Gruesome image shows victim's dead body surrounded by prayer beads .