From the moment we cross the Turkish border into Syria , evidence of the Islamic State in Iraq and Syria 's draconian and brutal rule lingers . More than a month after the group was driven from the town of Addana , residents here drive through the streets , pointing out where ISIS fighters carried out executions and left bodies to rot for all to see . `` That 's where they had one of their checkpoints , '' says rebel fighter Abu Sa'ed , pointing to a small concrete building on the side of the road as we speed past . ISIS arrived in Addana about a year ago , initially welcomed in the conservative town by Islamist fighters . But within a few months , ISIS had entrenched itself and begun exerting its harsh order through what one fighter calls `` terrorism and punishment . '' `` ISIS came in and took over one area and announced it was an Islamic state and did whatever they wanted , '' Abu Sa'ed says . In the passenger 's seat , fellow fighter Abu Jaafar sighs , his AK-47 trained out the window . `` They used to leave the bodies of people they executed at the checkpoint for days , '' he says . `` The corpses would rot . No one could avoid looking at them . '' Amid the civil war in Syria , another war is taking place -- one that pits moderate and Islamist rebels against radicals from ISIS , a group so radical that even al Qaeda has reportedly distanced itself from it . Both groups of fighters are opposed to the government of Syrian President Bashar al-Assad . For months , reports have been emerging from northern Syria about ISIS atrocities . In Addana , bullet holes riddle the walls at a former ISIS prison . Most of them are at the same level -- the average height of a man . `` Those are mostly from the executions , '' says Abu Jamal , another fighter . `` Others are from the battle . '' At the town 's courthouse , a fresh coat of white paint covers the black mark left by ISIS -- known to paint buildings black as they take over Syrian towns . Executions would take place out front . In the back , freshly dug dirt marks where some of the bodies were buried in mass graves . Abu Jamal points to a pile of burning trash . ISIS beheaded one of the top rebel commanders -- placing his head in that very spot -- in broad daylight when the market was packed with people as a warning : anyone who dared oppose them would have the same fate . In early January , rebel groups banded together and launched an offensive against ISIS in Addana and other areas in northern Syria . `` We had to leave the fronts with the regime , '' Abu Jamal says , `` and fall back to fight ISIS and liberate the already liberated areas . '' Still , many in Addana are too afraid to speak openly . So deep is their fear , they do n't even want to be seen with us . Next to the former prison , a family waits , hoping for closure . Volunteers shovel dirt from a grave they dug up before . Video filmed at the time shows four contorted corpses . It 's among many mass graves rebel fighters have unearthed . `` We found a foot , a shoe , and a jacket , '' Addana resident Ayoush Ali tells us . Her neighbor Mohammed Ismail joins us . His two younger brothers are missing , he says . `` It 's my brother 's jacket . He just went out to get sugar and tomatoes . '' A man drops a pile of children 's socks , covered in dirt , on the ground . `` His wife wanted socks for their kids , '' Mohammed says , still disbelieving . The day after we meet Mohammed , the bodies are dug up . It 's three of his brothers who were killed by ISIS . He had thought one of them was in jail . He crouches on the ground , covering his face , shoulders shaking as he sobs .
The radical opposition group ISIS was driven from Addana more than a month ago . Locals describe mass executions committed by the al Qaeda-influenced group . A war within a war is taking place in Syria , pitting rebel fighters against radicals from ISIS . The town is still reeling from the group 's yearlong brutal reign .