ISIS is tightening its grip on an estimated 3,000 Yazidi women and girls being held as sex slaves.
Most of them were taken captive in the summer of 2014 when the terrorists overran their villages in northern Iraq.
Women who managed to escape and Yazidi activists say ISIS has created a database of the captured women, which includes their photos and the names of their owners, to prevent them from escaping through the terror group's checkpoints.
"They register every slave, every person under their owner, and therefore if she escapes, every Daesh control or checkpoint, or security force - they know that this girl ... has escaped from this owner," said Mirza Danai, founder of Luftbrucke Irak, a German-Iraqi aid group.
ISIS is also murdering smugglers who attempt to rescue the women and girls.