The biggest question that has hung over the disappearance of these British mothers and their children is what could possibly have motivated them. Why would a parent believe that they and their children would be better off with Isis in the midst of Syria's civil war?
Usama Hasan, senior Islamic studies researcher at the anti-extremism think-tank, Quilliam, believes part of the explanation lies in the success of Isis's propaganda.
"There's this very romantic, idealised idea [among some Muslims] that Islamic State is some kind of utopia and a state of justice and paradise on earth," he said. "That features on a lot of the propaganda videos. Every mother wants the best for their children. If you look at the Isis propaganda online, they paint Raqqa and Mosul as peaceful places with functioning societies."