The defendant, known as "Nadine K" allegedly enslaved a 22-year-old Yazidi woman for five years, during the group's activity in Syria and northern Iraq.

Sky News has exclusively spoken to the Yazidi witness, known in court proceedings as Naveen al K, whose testimony is at the heart of the trial. She spoke, often through tears, about the harrowing ordeal she endured in a face-to-face interview from northern Iraq.

The defendant is believed to have travelled to Syria in 2014 to join the Islamic State group, along with her Syrian husband. He worked as a doctor for IS while she looked after the household, two daughters and the women they captured.

In 2015, they moved to the city of Mosul in Iraq, which by then was under IS control.

Naveen al K, whose full name cannot be revealed until the verdict is delivered later, claims she was enslaved, suffered regular violence, abused and was forced to cook and clean for the couple.

She is being represented by the human rights barrister, Amal Clooney. The defendant denies the charges.

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The family moved between Iraq and Syria as the fighting continued and coalition forces started to recapture land and defeat the terror organisation.

The couple were eventually arrested by Kurdish forces in March 2019 and Nadine K went back to Germany in 2021.

The Yazidi captive was eventually released and made it to safety after she was discovered in a sprawling holding camp in the Syrian desert by a Scottish documentary filmmaker, Alan Duncan.

'I cried...watching Naveen relive the horrors'

Speaking to Sky News Mr Duncan said: "I have been following Naveen on this journey for the last four years, from the moment we found her in the Al Hol camp and freed her from ISIS.

"I cried as I sat in the courtroom watching Naveen relive the horrors that she was put through.

"She had to recount intimate details to a foreign court, in front of people she didn't know, in a language she couldn't understand.

"She, like so many other survivors, never gave up hope. I hope this trial is a step towards closure."

Naveen Al K, whose mother died whilst she was in captivity, spent several days giving evidence at the trial in Germany, standing face-to-face with her alleged former captor.

Earlier this year the German parliament recognised crimes committed against the Yazidi people as genocide.

The country is believed to have the world's largest Yazidi diaspora and has actively pursued other cases of crimes committed against them.