In exclusive interviews, photos, and research, the AP has documented and mapped 72 mass graves of victims of the Islamic State. It's the most comprehensive survey so far, with many more expected to be uncovered as the group's territory shrinks. In Syria, the AP has obtained locations for 17 mass graves, including one with the bodies of hundreds of members of a single tribe all but exterminated when the group took over their region. For at least 16 of the Iraqi graves, most in territory too dangerous to excavate, officials do not even guess the number of dead. In others, the estimates are based on memories of traumatized survivors, ISIS propaganda, and what can be gleaned from a cursory look at the earth.
Still, even the known victims buried are staggering—from 5,200 to more than 15,000. Of the 72 mass graves documented by AP, the smallest contains three bodies; the largest is believed to hold thousands, but no one knows for sure. ISIS has made no attempt to hide its atrocities. In fact, it boasted of them. But proving what United Nations officials and others have described as an ongoing genocide—and prosecuting those behind it—will be complicated as the graves deteriorate. Justice has been meted out in at least one mass killing—that of about 1,700 Iraqi soldiers who were forced to lie face-down in a ditch and then were machine-gunned at Camp Speicher. On Aug. 21, 36 men convicted in those killings were hanged at Iraq's Nasiriyah prison. (Read more Islamic State stories.)