"Everything is still the same. The same people who joined (IS) are still in those neighbourhoods. How can we return and trust them again?" Khalaf said in an interview with AFP this week.

"Who will guarantee that genocide will not happen again, by perpetrators using another name?" she asked, speaking through a translator.

Khalaf was 18 when IS fighters arrived in her once peaceful village of Kocho in Iraq's northern Sinjar region on August 3, 2014.

Speaking on the sidelines of a summit for human rights defenders in Geneva, the young woman with long black hair and sorrowful eyes said she and her family never expected to be attacked.

"We hadn't harmed anybody, we hadn't offended anybody... We just wanted to live in peace," she said.

But the Kurdish-speaking Yazidis, who follow a non-Muslim faith, became particular targets of hatred for the Sunni Muslim IS extremists that seized Sinjar in 2014 and unleashed a brutal campaign against the minority that the United Nations has called a "genocide".

When IS jihadists descended on the village, they gave the Yazidis two weeks to convert to Islam -- or risk the consequences.

Khalaf, who has written a book about her experience titled: "The Girl Who Beat ISIS", described what happened when those two weeks were up.

- Taken to slave market -

"They gathered all of us in the village and they asked us to convert. We refused, and they started killing the men," she told AFP.

"That one day alone they killed more than 450 men and boys."

Khalaf's father and one of her brothers were among those killed, and she was abducted.

"When we were taken, they did everything to us. They raped women and girls as young as eight," she said.

Khalaf was taken to one of IS's infamous slave markets, where Yazidi women and girls were sold and traded as sex slaves across the jihadists' self-proclaimed and since-crumbled "caliphate" in Syria and Iraq.

"They picked the ones they wanted, just like they were at the supermarket or buying an animal," she said.

In captivity, Khalaf said she managed to remain strong despite undescribable torment, seeking inspiration in her faith and upbringing, and in her desire to provide support to the younger girls held and ravaged alongside her.

She said she never stopped thinking about escape, and after four months, a poorly locked door gave her and several other girls their chance to get away.

After a long and arduous journey, she finally made her way to Germany, which has taken in more than 1,000 Yazidi survivors, providing them with refuge and psycho-social support.

- 'Bringing IS to justice' -

Asked what her daily life is like now, she said it was focused on helping ensure recognition of the genocide committed against the Yazidis and "bringing IS to justice".

Baghdad declared victory over the jihadist group last December after a years-long battle to retake large swathes of territory the extremists seized in 2014.

But that is far from enough, Khalaf said, insisting: "I want to see IS and those who committed these crimes in international court."

She said she was consumed with thoughts of the estimated 3,000 Yazidi women and girls who remain in captivity, and of the thousands who have gotten away but remain stuck in poorly serviced camps in Iraq.

"They need help, they need treatment, and they are not getting that" in the camps, she said, warning that without support, "many will die from suicide".

She hailed Germany, Canada and Australia for taking in many Yazidi survivors, but said there was an urgent need for more countries to do their part.

She also called on the international community to help rebuild the villages destroyed in Sinjar and to provide protection to Yazidis interested in returning home.

"I could only consider going back once I see justice, an international court recognising this as a genocide, and with international protection," she said.

"Otherwise, how can we know we will not face another genocide?"