Christians from Iraq are leading efforts to document the atrocities and destruction left by the Islamic State (ISIS) in their homeland to make sure that the Muslim militants will be held accountable for their crimes someday.

In an interview with the German international broadcaster Deutsche Welle, Father Ammar of the Syrian Catholic Church, who works closely together with the Bishop of Mosul, said Christians in the city of Qaraqosh are trying to keep records of the crimes committed by ISIS militants, including the buildings they destroyed and defaced.

"We want to document everything, all the damage and destruction, before anything is cleaned. Already something has been changed, the IS slogans have been painted over," the Roman Catholic priest said.

He gave a concrete example of how the Islamic militants have desecrated a Catholic Church in Qaraqosh.

"They wrote their names on the wall of our Church of The Immaculate. And one of their leaders lived in the house of the church," he said, adding that another church, the Church of Mar Gorgis, was turned into a bomb factory.

The priest shared how much he is saddened by how the ISIS militants totally destroyed the landscape of Qaraqosh, including the destruction of hospitals that could have saved numerous lives of residents there.

"The first thing I saw was the hospital and I could not recognise it. The same for the church. I cried. That first feeling was so hard," he said.

Father Ammar added that Iraqi citizens are disappointed with their government's lack of effort to document ISIS' atrocities.

"They are angry that the government wants to clean up in Qaraqosh, to hide the crimes," he said.

At present, it has not been determined yet how many Christian residents of Qaraqosh are still missing after the ISIS invasion of the city. The estimates vary between 30 and 70. Their Christian families are still looking for them.