The beheading of Americans and British hostages shone a light on the brutality of the militant group ISIS, and may have helped hasten the US-led military campaign against the group. But little has been said about the thousands of people who have been captured or killed by members of the group as they moved through Iraq and Syria.

Among the militant group's untold victims are more than 3-thousand women and children of the minority Yazidi sect who are believed to be held captive in northern Iraq in various ISIS prisons.

Khider Domle, a minority rights activist in Kurdish Iraq, tells As it Happens' host Carol Off that he has been in daily mobile phone contact with some of the women, held as prisoners or slaves in different parts of Iraq.

Many are being held at one of former Iraqi Prime Minister Saddam Hussein's castles. Others say they are being held in villages under ISIS control, or in converted school buildings or makeshift prison camps.

Domle says that the women have described being taken by ISIS fighters as slaves, tortured and sexually abused. He says that lately boys as young as seven are being taken away to ISIS military camps to be converted to Islam and trained to fight.

Domle says that recent airstrikes in northern Iraq helped more than sixty Yazidi women escape their captors. But his pleas for Iraqi or Western help to free the thousands still held have gone unanswered.