“ISIS recently executed more than 200 of its own militants after they tried to break off and join al-Qaida, witnesses told Syrian human rights workers. The militants, apparently of Chechen and central Asian background, were more interested in fighting Russian and Syrian government troops than helping ISIS conquer the region.”
“An ISIS defector told the Syrian Observatory for Human Rights (SOHR) the men were marched to a natural hole in the ground in the countryside near al-Raqqa where they were murdered and their bodies dumped. Another 21 militants “of Caucasian nationalities” were gunned down by ISIS in August after they left their guard posts, SOHR reported.” (Coordination Center)

http://www.torontosun.com/2015/10/29/isis-executes-200-of-its-own-trying-to-defect-to-fight-russians