Authorities are working with the judiciary, forensic investigations, Iraq's Martyrs' Foundation, and the directorate of mass graves to carry out the excavation of the site of a sink hole in al-Khafsa, south of the northern city of Mosul, the state-run Iraqi News Agency reported on Sunday.
Ahmad Qusay al-Asady, head of the Martyrs Foundation's mass graves excavation department, says his team began work at Khasfa on August 9 at the request of Nineveh province's Governor Abdulqadir al-Dakhil.
The operation is initially limited to gathering visible human remains and surface evidence while preparing for a full exhumation that officials say will require international support.
After an initial 15 days of work, the foundation's Mosul teams will build a database and start collecting DNA samples from families of suspected victims.
Al-Asady explained that laboratory processing and a DNA database must come first to ensure proper identification. Full exhumations can only proceed once specialised assistance is secured to navigate the site's hazards, including sulfur water and unexploded ordnance.
Based on unverified accounts from witnesses and families and other unofficial testimonies, authorities estimate that thousands of bodies could be buried there.
Scores of mass graves containing thousands of bodies of people believed to have been killed by the extremist group have been found in Iraq and Syria.
At its peak, IS ruled an area half the size of the UK in Iraq and Syria and was notorious for its brutality.
It beheaded civilians and enslaved and raped thousands of women from the Yazidi community.
The group was defeated in Iraq in July 2017, when Iraqi forces captured the northern city of Mosul.
Three months later, it suffered a major blow when Kurdish forces captured the Syrian northern city of Raqqa, which was the group's de-facto capital.
The war against IS officially ended in March 2019, when US-backed and Kurdish-led fighters of the Syrian Democratic Forces captured the eastern Syrian town of Baghouz.
Rabah Nouri Attiyah, a lawyer who has worked on more than 70 cases of missing people in Nineveh, said his investigation points to Khasfa as "the largest mass grave in modern Iraqi history".
Attiyah said roughly 70 per cent of the human remains at Khasfa are believed to belong to Iraqi army and police personnel, with other victims including Yazidis.
He has interviewed numerous eyewitnesses from the area who saw IS fighters bring people there by bus and kill them.
"Many of them were decapitated," he said.
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