"Ana" was taken from her family home in Iraq by a group of Islamic State militants to a house converted into a makeshift slave market.

Key points: Yazidi women described being kidnapped by Islamic State troops and sold as slaves

Yazidi women described being kidnapped by Islamic State troops and sold as slaves A woman bought by Australian Khaled Sharrouf is seeking compensation in NSW's Civil and Administrative Tribunal

A woman bought by Australian Khaled Sharrouf is seeking compensation in NSW's Civil and Administrative Tribunal A refugee advocate and child genocide survivor says the case is about accountability

She watched on in horror as men arrived every few hours to choose which woman they would purchase.

"They would come and just pick whichever girl they wanted and just grab her by the hand and drag her away," she said.

It has been five years since IS militants left their bases in Syria and Iraq and stormed into Sinjar in northern Iraq to begin a campaign of unimaginable horror.

But Ana can still hear the sounds of girls crying as they were taken away by their captors from the Mosul house.

"They would just grab her by the hair and drag her behind them. They would take off their shoes and whatever they could get their hands on and hit her to force her to go," she said.

Ana (left) washed clothes, cooked and cleaned for Khaled Sharrouf. ( ABC News: Lincoln Rothall )

The remaining women at the house were eventually taken to Raqqa in Syria.

Ana remembers a big white hall in a forested area surrounded by water, where dozens of other Yazidi girls and women were being held.

She was there for 17 days before the man she knew as Abu Zarqawi al-Australi came to buy her.

This was Khaled Sharrouf, a convicted terrorist who went from Sydney to Syria.

Ana does not know how much Sharrouf paid for her, but she had heard of other girls being sold for between $30 and $60.

"He pulled out a gun, pointing it at my head. I said, 'I am not afraid,' and he said, 'Are you an infidel not to be afraid of being killed?'"

Australian jihadist Khaled Sharrouf left Sydney for Syria so he could join Islamic State. ( Supplied )

He grabbed her hand and dragged her away.

"I told him I don't want to come … and he said, 'Come with me. I promise you won't be by yourself. You'll have other friends there," she said.

Ana's heart leapt when she met Sharrouf's three other Yazidi slaves. She was relieved to not be alone.

"He took me to a room and told me he was going to take me to my friends. When I got there, I saw three Yazidi girls," Ana said.

But although she was allowed to stay with the other women, life in the Sharrouf house "was like being in a prison".

"We lived in constant fear that they were going to sell us at any minute."

Sharrouf terrified the women and they were not allowed outside, Ana said.

"We would wash their clothes and clean the house and cook. Sometimes we would cook four, five, six times a day," she said.

Every day the women spoke about escaping, plotting a way out of their nightmare, praying together that they would find a way out.

The 'legal gap' for the victims of Islamic State

Little is known about Ana's escape from Sharrouf's house.

She cannot go into too much detail, only to say that the women had a phone and knew of some numbers to call.

That she was able to survive is miraculous given what other Yazidi women endured when they tried, and failed, to escape.

A United Nations investigation of the Yazidi genocide found shocking examples of brutality meted out to women who tried to run away.

Yazidi women and children who managed to escape Islamic State militants ended up in refugee camps in Iraq. ( Reuters: Youssef Boudial )

One woman, held in northern Syria, reported that her "owner" killed her children after an escape attempt.

The fighter continued to rape her for more than six months after her children's deaths.

After her escape, Ana was taken to Germany three years ago, along with scores of other Yazidi women, thousands of kilometres away from her ancestral home.

"We have been persecuted many times, suffered a lot," she said in a quiet voice.

"With such bad experiences, coming to a new country is not easy … we have psychologists who helped us, and they are still doing so."

Although she is in Germany now, it is in Australia where her case for compensation — along with other women he enslaved — is being considered.

A team of international lawyers and British-based non-government organisation the Lotus Flower is pursuing an ambitious case in New South Wales, asking whether survivors like Ana could be eligible for victim's compensation.

Sharrouf was killed in an airstrike in 2017 and Australia had revoked his citizenship in 2015.

For victims of Islamic State fighters, it may seem impossible to seek justice after what happened to them, especially in cases where the persecutors are now dead.

Refugee advocate Taban Shoresh, who is helping to support the women, said the international community owes it to Yazidi women to try to find a way.

Ms Shoresh, a child genocide survivor during Saddam Hussein's regime, said compensation was unlikely to amount to much, but the case was about accountability.

"There is a massive moral outcry of the injustice that the Yazidi women and girls have faced … but actually in reality, there's a massive legal gap," she said.

Refugee advocate Taban Shoresh is urging the international community to help the Yazidis. ( ABC News: Lincoln Rothall )

"If you've got a collective of foreign fighters, if you collectively pool all their assets together and sell their frozen assets … you could create some sort of remedy".

Ana told the ABC the case is important to her, because the women "don't want to be silent".

"Australia could really lead the way in implementing this, it's a practical solution that enables the women to have some form of justice, for their rights to be accepted," Ms Shoresh said.

'Why are the ones who raped and killed living a normal life?'

Dalal Khero, who was 17 when she was enslaved, is angry that so few Islamic State group militants have been tried after returning to European nations.

Dalal Khero was enslaved as a teenager but has made a new life for herself in Germany. ( ABC News: Tim Stevens )

"I'm not afraid because the period of fear has passed. I've been through that, what had happened to me is a reality. I was raped," she said.

"Germany has done a lot for us — gave us a new life — but I see that not even [Iraq] is doing anything for us. But Germany can do something."

Yazda, an international Yazidi support organisation, the UK and Germany, has been gathering the stories of women like Ms Khero.

Tens of thousands of Yazidis who sought refuge in Germany since 2014 are witnesses to war crimes, according to Saeed Qasim Sulaiman, who works with Yazda across the country.

"They do have evidence [and] there are hundreds of survivors who are ready to testify about the crimes," he said.

Saeed Qasim Sulaiman is a Yazidi refugee who has been helping genocide survivors seek legal help ( ABC News: Bridget Brennan )

But he fears that time is running out to bring alleged war criminals to justice.

"I don't know until when the survivors will have the strength and will remember those stories," he said.

In Munich, a woman known only as Jennifer W is on trial for war crimes and murder, accused of letting a five-year-old Yazidi girl who she had enslaved die of thirst.

Still, Mr Sulaiman said many Yazidis believe action has been too slow.

"Why the ones who killed, raped, sold many women and children are still living a normal life?" he asked.

Survivors find healing in friendship

Salwa Khalaf Rasho (left) is slowly healing from her ordeal with the help of her friends. ( ABC News: Bridget Brennan )

In Freiburg im Breisgau, in south-west Germany, Salwa Khalaf Rasho sets fruit and tea on a table carefully laid out with meeting agendas and briefing documents.

The 21-year-old came to a brightly lit building on the edge of the city to meet with other Yazidi women, all who were once deemed slaves for the Islamic State group.

The women are here to discuss the formation of a new organisation which they would run together to help other genocide survivors.

Ikhlas Khidr, 19, was brought to Germany four years ago, after she escaped slavery in Syria.

"I love Germany, German people. They respect us a lot. What Germany did for us no one did," she said smiling.

Ikhlas Khidr came to Germany from Iraq four years ago. ( ABC News: Bridget Brennan )

Her eyes lit up when she explained how her time with other Yazidi women in Germany has helped to heal her.

"Everyone of them is very, very brave," she said.

"What ISIS did to us — rape, selling us — there wasn't anything left that they didn't do to us. We don't want to physically fight them, but we want to fight them educationally and by law to get our rights and by justice."

When Ms Khalaf Rasho arrived in Germany a little over a month after she escaped from slavery, she was deeply traumatised, and unsure if she wanted to leave her family behind.

Salwa Khalaf Rasho was kidnapped by the Islamic State group as a 16-year-old. ( ABC News: Lincoln Rothall )

"At that time, emotionally I was in need of my family. I could not speak the German language and I did not have any friends here," she said.

For a year, she was frozen, unable to do anything for herself, scared that she may never get better.

"Psychologically I was not good, even I was forgetting things."

Now, her memories are clear and deeply painful.

Ms Khalaf Rasho was taken to Mosul to be a slave to an Islamic State militant, his wife and sons; she was a witness to life under the Islamic State group.

"Here at school we were reading about the history of Germany and Hitler's genocide and see how they controlled people step by step, and IS was doing the same," she said.

In Germany, she has found a new life working and studying, but her trips home to Iraq will drive her work in Germany to advocate for the rights of Yazidis.