British jihadists fleeing Mosul could face the death sentence in Iraq's makeshift courts

There are nearly 40,000 names on the list, 80 per cent of them in connection with terrorism.

It can be an arduous process, particularly when the suspect has a common name. And many get wrongly caught in the dragnet.

Those who are deemed to warrant further investigation are kept in makeshift prisons in houses and mosques around Qayyarah, 40 miles south of Mosul, pending either release or trial.

The Iraqi authorities are in uncharted territory trying to deal with them all.

The Qayyarah terrorist investigations court, which sits in a large stone house in the centre of Qayyarah only recently retaken from Isil, is the only one deciding the fate of those accused of links to the jihadist group.

The court cannot keep up with the growing number of detainees. It has heard more than 150 cases since it opened in late September, and Judge Abu Iman says he is ruling on up to eight a day.

“I see some in here as young as 16 and some as old as 60,” says Judge Iman, using a pseudonym as he is afraid of reprisal. “Some are easier to decide than others.

“We have to differentiate between supporters and fighters,” he says, sitting behind a desk in the house’s stone-cold reception room, which has been without electricity since they moved in. “So if someone offered Daesh help in some way that would be different to fighting for them.

“As examples, I heard the case of a young man who had worked as a cook for the fighters as he was poor and needed money to feed his family.

“Another who was here last Thursday got arrested by Daesh and put in prison. They told him that if he fought with them he would be freed. He joined, but then fled 10 days later.

“None of them stand in front of me proud, admitting to being a member of Daesh,” he says. “I cannot have too much sympathy for these excuses though, otherwise I’d let them all walk free.”

If there are at least two “witnesses” testifying against a suspect it is enough to refer them up to a higher court for sentencing.

Those found to have offered material support to the militant group face 15 years in prison. Convicted fighters could be given life, and in cases where it is proven they carried out particularly heinous crimes, execution can be ordered.

Judge Iman reserves the right to pardon those he believes joined Isil under duress and did not kill anyone or damage any property.

So far all the defendants have been Iraqi nationals, but as the army pushes further into Mosul they are sure to come across some of the many thousand foreign recruits believed to be holed up inside the city.

He warns that the foreigners, which are thought to include at least 100 Britons, would be tried “just the same as locals”. “They have committed crimes against Iraqis so they should face local law,” he says.

Intelligence officials estimate that some five per cent of the men that have fled the city of one million have been held on suspicion of cooperating with Isil.

So far Iraqi forces have only liberated a small section of Mosul. Once the whole city has fallen, thousands could end up being detained.

“Our prisons are already full, I don’t know how we’ll manage,” says Sergeant Abu Ali, standing guard at the court. “Soon we will have to build more to accommodate them all.”

Amnesty International has expressed concern about the process.

"They rely heavily on informants," said Donatella Rovera, senior crisis response adviser for the human rights group, warning the trials could create a witch hunt.

“It’s an opportunity for people who want to take revenge on someone else,” she says.

“There's no awareness that the testimony of someone needs to be backed up by appropriate evidence.

“The system is just so incredibly under-resourced. Even if you had very skilled people there's no way you could do a good job even in those circumstances."

But the staff at Qayyarah court are under pressure to achieve results. “What can we do?” shrugs Sgt Ali, ”it’s an impossible situation.”