Enslaved by ISIS along with her mother, 5-year-old Rania died while chained outside a window in the searing heat of Iraq's summer as punishment. Nearly five years later, a court in the German city of Frankfurt has put a 27-year-old Iraqi man on trial for her murder. Taha Al Jumailly is being tried on charges of genocide and murdering the child from Iraq's Yazidi minority who he held as a slave. He is also accused of crimes against humanity, war crimes and human trafficking. He gave no initial response after being formally advised of the charges against him at the start of the trial on Friday. His wife, a 28-year-old German named Jennifer Wenisch, has been on trial for a year at a Munich court. She too is charged with the murder of the Yazidi girl, who the couple are believed to have allowed to die of thirst in the Iraqi city of Fallujah in 2015. Rania's mother, identified only by her first name Nora, has repeatedly testified in Munich about the torment visited on her child. The Yazidis, a Kurdish-speaking ethnic and religious minority, were specifically targeted and oppressed by ISIS, which considered its members apostates. The group forced the women and girls into sexual slavery, recruited the boys as child soldiers and murdered hundreds of men. The United Nations has called the ISIS assault on the Yazidis’ ancestral homeland in northern Iraq in 2014 a genocide, saying the 400,000-strong community "had all been displaced, captured or killed”. Court documents allege that Al Jumailly joined ISIS in March 2013, holding different positions within its hierarchy in the group's "capital" in the Syrian city of Raqqa, as well as in Iraq and Turkey. German prosecutors say the accused bought a woman belonging to the Yazidi minority and her 5-year-old daughter as slaves at the end of May or beginning of June 2015. He then took them to his home in Fallujah, where they were seriously maltreated and at times deprived of food, the prosecutors allege. "They were not allowed to leave the house unaccompanied. He forced them to wear a full veil, and did not accept the child's name because it was a name of the infidel," chief prosecutor Anna Zadeck said on Friday. "Both were regularly beaten. The woman has suffered pain in her shoulder ever since. The child once had to stay in bed for four days after being beaten." In the summer of 2015, after a string of such abuses, the young girl was chained by Al Jumailly to the window of a house where she lived with her mother, as punishment for having wet the bed, prosecutors said. She died of thirst in temperatures as high as 50°C. The couple also forced her mother to walk barefoot on the scorching ground outside, inflicting severe burns, the prosecution claims. Mother and daughter had been kidnapped in the summer of 2014 after ISIS invaded the Sinjar region of Iraq. They were repeatedly sold on ISIS "slave markets", prosecutors say. The Frankfurt case is expected to last until at least August, and is being heard under tight police guard. Al Jumailly was arrested in Greece in May 2019, before being extradited to Germany in October, where he has since been held in pre-trial custody. His wife was arrested while trying to renew her identity papers at the German embassy in Ankara in 2016, and deported back to Germany. She is on trial for murder, war crimes and membership in a terrorist organisation. Wenisch, 28, grew up a Protestant in Lower Saxony state and converted to Islam in 2013. She is alleged to have made her way to Iraq through Turkey and Syria in 2014 to join ISIS. In 2015, as a member of the group's "morality police," she patrolled parks in Fallujah and Mosul, armed with an assault rifle and a pistol as well as an explosive vest and looking for women who did not conform with its strict codes of behaviour and dress, prosecutors said.<br/> Both Lebanese-British lawyer Amal Clooney and Yazidi activist Nadia Murad – herself a survivor of ISIS sexual slavery and a 2018 Nobel Peace Prize winner – have represented the mother of the young girl at Wenisch's trial. The two women lead an international campaign to classify ISIS crimes against the Yazidi community as genocide. But proving before a court that genocide has taken place is difficult. The explicit will to destroy a group such as the Yazidi must be demonstrated to judges' satisfaction. "There is often no order to wipe out" a group, University of Leipzig legal expert Alexander Schwarz told Agence France-Presse news agency. "There are no written instructions where 'exterminate the Yazidi' appears."