A few months ago, when the Isis caliphate had been reduced to a string of towns and villages along the Euphrates River, there was still a glimmer of hope.

For the families of more than 3,000 Yazidis who were taken into slavery and are still unaccounted for, there was a possibility that their loved ones could be living among the population, unable to escape, or waiting for the right opportunity.

But as the caliphate has slowly collapsed, so have the hopes of finding the missing.

“We have had the same number of missing for years now. The problem is, not many are coming back,” said Ahmed Burjus, deputy executive director of Yazda, a Yazidi advocacy group.

“We were hoping that many people would be liberated from Baghouz, but only 50-60 [Yazidis] have escaped,” he told The Independent, referring to the last village under Isis control.

Tens of thousands of women and children have fled the shrinking Isis territory in eastern Syria over the past few weeks, but most of them have been families of fighters or sympathisers. Only a few dozen Yazidi captives have been among them.

Those who have emerged have done so after sneaking out among the families of those who tortured and enslaved them. Defiant Isis women have been filmed after fleeing Baghouz shouting the terror group’s slogans and justifying the enslavement, while not far away Yazidi women have burnt the black abayas they were forced to wear, after tasting freedom for the first time in years.

The Syrian Democratic Forces said Monday that it had 16 freed Yazidis – including children – in an operation days earlier. Last week, Salwa Sayed al-Omar was among them. She fled the enclave with two Iraqi boys pretending to be her brothers, according to Reuters.

“They took women, abused them and killed them,” she said, describing how jihadists bought and sold their Yazidi captives or passed them around as sexual slaves.

“They took me from Iraq. They captured us on the road and said ‘we won’t do anything bad to you, but you must convert to Islam’. We were afraid to be killed so we converted,” she said.

A small number of boys have escaped, too. Hundreds of them were taken along with the women when Isis overran the Yazidi heartland of Sinjar in 2014, and were brainwashed by the group.

Despite these escapes, in the last days of the caliphate, Yazidi groups have had to confront the possibility that they will never find the answers they are looking for. But they are not ready to give up.

Yazda is now calling on the international community and local authorities to widen the search, looking in the camps holding tens of thousands of Isis families, and in areas liberated from the group years ago.

“They have found a Yazidis in Baghdad, in Mosul, even in Turkey two days ago. We believe many are living in these places and they cannot escape,” said Mr Burjus.

“They are forcing Yazidis to wear veils and cover their faces, and there must be many children who were very young when they were kidnapped and have forgotten who they are,” he said. “Most of the women and girls from villages and they don’t even know how to use internet. So it’s difficult for them to escape.”

Mr Burjus said a specialist task force could go into these areas and search for missing Yazidis.

“Around Mosul and Nineveh, we think many Yazidis are still there,” he said. “There has to be steps by intelligence services to get into the local community to search, offer rewards for missing Yazidis. There is no plan like this,” he said.

The lack of closure has only added to suffering the community has endured since Isis carried out its most heinous crime five years ago.

In the summer of 2014, shortly after Isis declared its caliphate, the group carried out a murderous rampage against the Yazidi people in their traditional homeland in northern Iraq.

The attackers killed thousands, and took more than 6,000 women and children as slaves. The UN would later declare the attack on Sinar, and the ongoing enslavement of Yazidi women, a genocide.

The Yazidi children of Isis' training camps

Yazidi groups have consistently complained that not enough has been done to find and rescue the thousands of women who were taken.

"It is outrageous that thousands of our women and girls have been missing since 2014 and it has not been a priority or main area of discussion with the global coalition and the international community," Pari Ibrahim, founder of the Free Yazidi Foundation, told The Independent recently.

"We can understand that this is a war zone situation, and because of that, maybe locating and rescuing the women is very difficult. So we understand and appreciate that. But we still feel that this should have been considered important and necessary. Instead, our women and girls were being tortured in excruciating agony, month after month, year after year."

There is a concern, too, that the neglect will continue after the battle is won, and that this will have an impact on the quest for accountability. The current debate over the fate of British Isis members is just one example, according to Mr Burjus.

“It’s sad to see the international community, with all their resources, constantly having debates about whether to allow Shamima Begum to come home. No one is talking about justice,” he said.

“If you are not punishing them you are telling them to come kill people, the field is yours. Letting people get away with their crimes is not reconciliation,” he added.