ISIS used a sinkhole outside Mosul to dispose of its victims, a place already used by Saddam Hussein to make people disappear.
The Daily Telegraph: Horror of Mosul where sinkhole became mass grave for 4,000 of Isil’s victims

ISIS used a sinkhole outside Mosul to dispose of its victims, a place already used by Saddam Hussein to make people disappear.
While neighbouring Kurds make headlines, tensions simmer quietly in Iran as an exiled Kurdish group seeks to capitalise on growing discontent.
Eventually the stench of death was too much even for ISIS. They covered it, mined it. The Iraqi government won’t touch it. […]
Mass graves and the survivors of massacres tell of the horrors inflicted on the Yazidi minority by ISIS.
Thousands of Yazidi women and children were kidnapped by ISIS. A group of smugglers are taking great risks to get them back.