(CNN) – Sinjar is yielding up its secrets — the whispers of those who prayed as they were killed. Grief for those captured and never seen again. Mahama al-Shangali is the mayor of this town of fewer than 90,000 people in northern Iraq, in the heart of Yazidi country. When ISIS swept through the Yazidi homeland, it was along the road into Sinjar that men, women and children who had been rounded up from the surrounding villages were driven.