There is a battered-looking track on the edge of Hammam al Alil called Agricultural College Road.

But Agricultural College Road doesn't have a college anymore.

The campus was damaged by coalition airstrikes - then finished off by the men from Islamic State as they retreated to the nearby city of Mosul.

However, at the end of this dilapidated thoroughfare, we could see a small group who had parked up their cars.

Twenty or so people were examining a litter-strewn field, scattered with dead bodies.


Image: Hundreds are believed to be buried in the litter strewn land

This stomach-turning spot, at the far end of campus, was used as a place of execution by the self-described Islamic State.

On the surface of this hardscrabble lot there were 20 or 25 bodies - and limbs and skulls and bits of clothing poked through the ground.

A forensics officer from Baghdad turned up and he looked troubled at what he had seen.

"I am sorry, I feel terrible to tell you this, but some bodies have been mutilated and some have been beheaded. A number of corpses have been eaten by animals as well," said Mohammed al Tamin.

Sky News looks inside IS prison in Hammam al Alil

We found a local man called Ahamad al Jobbori searching through the dirt and pieces of litter.

A corporal in the Iraqi Army, he had escaped Hammam al Alil before IS rolled in two-and-a-half years ago and he wanted to know what had happened to his relatives.

"There are two of my cousins here - the sons of my uncle - and many other friends too," he said.

"You know the angel of death was here, killing, killing, killing. No one knew why. They terrified the people, they horrified them. But they didn't care."

Image: A room used as a prison cell in Hammam al Alil where men had to sleep standing up

On Friday the United Nations Human Rights office confirmed the existence of a mass grave in Hammam al Alil, containing "at least 100 people".

But Mr al Jobbori told me there were more than 300 buried at the site we stood on - and there were other places on campus where corpses have been left, he said.

Residents knew something was going on at the college. They saw people in blindfolds being marched up there - as well as gunshots crackling from the grounds.

But only one family in Hammam al Alil went looking for their missing loved ones.

Image: Muqtadar's older brothers Hussain and Aboud were killed by IS

Thirteen-year-old Muqtadar Ahmed saw the bodies of two of his older brothers dumped off Agricultural College Road.

Hussain and Aboud Ahmed had been executed by IS because they had previously served in the Iraqi Army, says the family.

The boys' uncle, Asaad al Hindi, decided to risk his own life by going to get them in the middle of the night.

It took two trips with a donkey to get them but Mr al Hindi was fortunate - he didn't get caught.

"One was left in a small ditch. The other was right beside him. It was fresh - they'd just been killed," said Mr al Hindi, staring into the distance.

Image: Asaad al Hindi with his 13-year-old nephew Muqtadar (R) in Hammam al Alil

Eventually, the two young men were buried in the local graveyard, but not before another family member was beaten after trying to dig their graves.

Uncle Assad looked like a man who had simply had enough.

"My feelings have passed any level of anger," he said.

"I have reached the state where this is normal. I don't have feelings anymore."

Image: The dead boys' mother was inconsolable

We met the dead boys' mother as we left the family house and she was, understandably, inconsolable.

"Bring the photos of Hussain, get the picture of this flower, my clean, honest boy," cried Mrs Ahmed.

"Why won't they come back? Look, I am so tired."

Her eldest son, Mahmoud, is still missing. The Ahmeds haven't been able to find him anywhere.

Militants from IS left this town a few days ago, but the terror will remain in this traumatised community for years and years to come.