Iraqi forensic teams have described how they wept as they began to excavate 12 graves, believed to be the final resting place of as many as 1,700 soldiers killed in cold blood by ISIS last summer. The teams began the gruesome task of uncovering the bodies of the young army recruits of Camp Speicher, slaughtered by the Sunni ISIS militants as they surged across northern Iraq for the 'crime' of being Shi'ite. The deaths showed Iraqis that Islamic State fighters, who have also attacked ethnic and religious minorities as well as fellow Sunni Muslims opposing them, were a threatening new kind of foe. Scroll down for videos . Distraught: A soldier prays at the site where hundreds of his fellow fighters are thought to have been buried . Discovery: The graves were found last Wednesday on the late Saddam Hussein's presidential compound . Heartbreaking: The highest estimate for the number of recruits killed in the Speicher massacre is about 1,700 . For almost 10 months, their devastated families have been left wondering what became of their sons and brothers who had been marched through Tikrit, once Saddam Hussein's stronghold of support. The only clues they had were videos posted by the jihadists on social media sites, showing them being machine gunned down in their hundreds. But now it seems their final resting place may have at last been discovered, after 'dozens' of ID cards belonging to the army cadets were found at the late dictator's presidential compound last Wednesday. Today, the first of the 12 mass graves on the banks of the Tigris River began to give up their terrible secrets, days after Islamic State's fighters were driven from the city by Iraqi forces and Shi'ite paramilitaries. Those who began digging up the corpses today described the scene as 'heartbreaking'. Khalid al-Atbi, an Iraqi health official working with the forensic team sent to Tikrit, said: 'It was a heartbreaking scene. We couldn't prevent ourselves from breaking down in tears. 'What savage barbarian could kill 1,700 persons in cold blood?' Horror: Images like this one of the soldiers being led through Tikrit shocked Iraq and the world . Mourning: A soldier prays where the blood of Iraqi soldiers fell at Camp Speicher . Final resting place: Initial investigations reveal these are the bodies of the young cadets, a worker has said . Closure: Some of the people who lost loved ones in the massacre have expressed relief at the discovery . Mr al-Atbi added: 'We dug up the first mass grave site today. 'Until now we found at least 20 bodies. Initial indications show indisputably that they were from the Speicher victims.' But despite the horrifying scenes uncovered in the compound, families - who often grow angry at Iraq's political class for failing to provide them proper answers - have expressed releif their loved ones have been found. 'The only positive thing is the victory in Tikrit,' said Ali Hamad, whose cousin Kamal went missing at Speicher. 'We are happy. At least the families will soon know the fate of their sons and cousins,' he said. Anger: Families have often grow angry at Iraq's political class for failing to provide them proper answers. Pictured: A solider prays at the site today . Relief: 'At least the families will soon know the fate of their sons and cousins,' said one relative .
WARNING: GRAPHIC CONTENT .
Graves were identified last week after 'dozens' of ID cards found nearby .
Cards belonged to army recruits massacred by ISIS in cold blood last June .
Forensic teams have already dug up 20 bodies and expect to find far more .
'We couldn't prevent ourselves from breaking down in tears,' says worker .