An analysis conducted by Human Rights Watch of photographs and satellite imagery strongly indicates that the Islamic State of Iraq and Syria (ISIS) conducted mass executions in the northern Iraqi city of Tikrit after seizing control of the city on June 11, 2014.

Preliminary evidence suggests that ISIS killed between 160 and 190 men in at least two locations between June 11 and 14. Photos on the HRW website show rows of men lined up alongside trenches at the two sites, who are then shot by ISIS gunmen. According to HRW, the death toll could be much higher, however "the difficulty of locating bodies and accessing the area has prevented a full investigation."

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On June 12, ISIS claimed on its now-closed Twitter feed to have "exterminated" 1,700 Iraqi troops. The same day, the group posted videos showing hundreds of captured men in civilian clothes:

HRW also spoke with one man who fled Tikrit after the killings took place. From the roof of his home, the man watched armed members of ISIS load captured men into military trucks:

I saw them with my own eyes. It was late afternoon. It was a long line. I saw about 10 armed gunmen with their guns pointed at the line of men, walking them to military trucks. Some of the gunmen had masks and others showed their faces. The [captured] men were not handcuffed. They wore civilian clothes.

The man was later told by other Tikrit residents of bodies floating in the Tigris River.

Read the full Human Rights Watch report here.

Contact Senior Opinion Editor Francesca Bessey here; follow her here.