Pictures emerging from the city of Raqqa in northern Syria show how an Al Qaeda splinter group has been carrying out public "crucifixions" in areas under its control. The Islamic State of Iraq and the Levant (ISIS) - a group considered so brutal it was booted out of Al Qaeda, which was worried about the harm it would cause to its image - has suffered numerous setbacks in Syria in the past few months, as other rebel groups have turned on it, accusing it of working for the Assad regime to undermine the opposition. But it still has Raqqa firmly in its grip, and reports of the strict imposition of Sharia (Islamic law) have included executions, amputations and lashes. The few remaining Christian families in Raqqa were recently given a choice between conversion to Islam, death, or the acceptance of a special jizya tax for infidels. They chose the latter. But one of the most gruesome illustrations of ISIS's brutal rule emerged on Tuesday, when pictures of two men crucified in public - with children standing just feet away - emerged on Twitter. The bloodied corpses appear to have been bound to the crucifixes with rope, and were likely executed beforehand. The pictures were posted by both pro- and anti-ISIS groups, with the former gloating over them and citing the images as proof of ISIS's firm grip on the area, and the latter citing them as proof of ISIS's brutality. "We just executed 7 spies trying to plant bombs on cars of the ikhwa [brothers - ed.]. Massive turnout," read one message. Other tweets, cited by The Daily Beast , focused on mocking the two condemned men. "lol become new false jesus", tweeted one in response to the pictures posted on the account of an ISIS supporter, to which the original poster responded: "the spy next to him started urinating as soon as we tied him up, about 10 minutes after he was killed." It was not clear whether the alleged "spies" were accused of working for the Assad regime or rival rebel groups. This is not the first time ISIS has used crucifixion in Raqqa; just last month the group crucified a suspected thief. And at least one official Al Qaeda franchise - Yemen's Al Qaeda in the Arabian Peninsula (AQAP) - was accused by rights group Amnesty International as far back as 2012 of crucifying condemned men, as well as imposing "cruel, inhuman and degrading punishments… including summary killings, amputations and floggings" in areas under its control.