Yazi Mohamoud pleaded with jihadists to release her son Hekmat but he is still missing today

The demise of the jihadist empire that spirited away his teenage son could have been reason to rejoice but, for Abdelsalam Mohammed, with the fall of Baghouz came a crushing disappointment.

The eastern Syrian hamlet was the Islamic State group's last bastion but for the relatives of many missing people it was also one of the last places where their loved ones might have stayed alive.

In Abdelsalam's Kurdish village of Sherane, many families lost somebody to the jihadists when they rampaged across the region five years ago and spread their rule of terror in swathes of Iraq and Syria.

"We thought: 'Baghouz will fall, he's going to come back'. But he's still not home," he said.

Kurdish-led forces last week defeated jihadist fighters defending the last scrap of the so-called "caliphate" in Baghouz, ending IS territorial control in the region.

Tens of thousands of people, most of them jihadists surrendering but also some of the civilians they abducted and enslaved, poured out of the besieged enclave in recent weeks.

Sitting in his backyard, Abdelsalam recounted the fateful day in February 2014 when his 19-year-old son Mohammed left the village and joined a group of 150 people heading to Iraq to look for work.

The convoy was stopped at an IS roadblock and he never saw his son again.

- 'Worse than death' -

The young men were taken to prison in Raqa, the city that later became the de facto Syrian capital of IS's self-proclaimed proto-state.

Half of them were released nine months later but not Mohammed.

"Up until now, we haven't had any news," said Abdelsalam, who wears a red and white headdress and a grey suit jacket worn threadbare at the seams over his traditional gown.

Mass graves believed to contain thousands of victims have been unearthed in territory retaken from the jihadists

When the Syrian Democratic Forces announced the death of the "caliphate" on March 23, a delegation from Sherane visited the Kurdish administration in the nearby city of Kobane.

"They told us there was no information," Abdelsalam said.

Bereavement hangs like a cloud over Sherane, a farming village nestled in Syria's Kurdish heartland, surrounded by lush green plains and olive groves.

Almost each one of its modest concrete homes is haunted by the ghost of somebody who went missing at the hands of IS jihadists or was killed in battle.

"When someone dies, we know they're gone. But this is worse than death," the greying father said.

According to the Syrian Observatory for Human Rights monitoring group, IS abducted thousands of people in both countries when it overran the region in 2014.

Among them are a few well-known cases of foreigners, such as British reporter John Cantlie and Italian Jesuit priest Paolo Dall'Oglio, whose fates remain unknown.

- Mass graves -

Nadim Houry, from the New York-based watchdog Human Rights Watch, argued that the creation of an investigative commission should be a priority.

"It takes time to build up these mechanisms and to provide answers," he said. "The right of families to know is clearly enshrined in international law."

Abdelsalam Mohammed's son disappeared after he was stopped at a jihadist roadblock five years ago

Dozens of mass graves containing the bodies of thousands of people executed by IS have been found in Iraq and Syria but the identification process is slow, costly and complicated.

Houry argued the US-led coalition that backed the SDF's military drive against IS should offer support to local initiatives aimed at resolving the cases of the missing.

In Sherane, Adnan Ibrahim also saw his hopes of finding his younger brother Hekmat fade last week when the mass evacuations from Baghouz dried up.

His brother was returning from his work on a water well drilling in May 2014 when his bus was stopped by the jihadists near the city of Manbij.

Hekmat's family soon lost any trace of him and his wife took their two children and moved back in with her father.

"Every time somebody made it out of IS custody, we would go to see them to try to find out," the 56-year-old said.

His elderly mother went to Manbij twice to plead with the jihadists for her son's release -- in vain.

In their home's courtyard, framed by blue-painted walls, she knelt in prayer and then got up to fetch a picture in which Hekmat, wearing his military uniform, looks sternly at the camera.

"We still have hope," Adnan said, hesitantly. "But it's not easy."